The Order-to-Cash process, often abbreviated as O2C or OTC, is one of the most important end-to-end processes within an organisation. It connects Sales, Logistics and Finance and describes the journey from an incoming customer order through delivery and invoicing to payment receipt and the posting of the receivable.
Because several departments and systems are involved, companies often face media disruptions, waiting times, incorrect master data, delivery or billing blocks, unresolved receivables and manual rework. A well-designed Order-to-Cash process should therefore do more than simply process orders correctly. It should help companies convert revenue into liquidity faster, reduce errors and provide customers with a seamless process experience.
IBM defines Order-to-Cash as the process from the customer order through fulfilment and payment receipt to recording the completed sale. The process typically involves Sales, Customer Service, Credit Management, Logistics and Accounts Receivable.
The topic is also becoming increasingly important for SAP organisations. SAP S/4HANA supports key process steps such as sales order processing, credit checks, delivery, goods issue, billing, receivables management and incoming payments. In addition, solutions such as SAP Signavio, SAP Cash Application, SAP Document and Reporting Compliance and current AI capabilities provide further tools for organisations looking to digitalise the Order-to-Cash process, analyse it and gradually automate it.
This article explains which Order-to-Cash process steps are typically involved, what an SAP Order-to-Cash process can look like, what role e-invoicing plays and how organisations can optimise the Order-to-Cash process.
Key Facts About the Order-to-Cash Process
In the narrower sense, the Order-to-Cash process begins when a customer order is received or created and ends when the payment is received, allocated and financially posted. Earlier activities such as lead generation, quotation creation, price negotiations and contract conclusion are generally part of the broader Quote-to-Cash or Lead-to-Cash process. IBM and Zuora also distinguish O2C from Quote-to-Cash accordingly.
The following points are particularly relevant for organisations:
- An efficient Order-to-Cash process connects Sales, Logistics, Billing and Accounts Receivable.
- Automation reduces manual handovers and can shorten the time between order receipt and payment.
- SAP S/4HANA supports an integrated document flow from the sales order through delivery and billing to Accounts Receivable.
- E-invoices are increasingly becoming an integral part of billing and compliance within the outbound process.
- KPIs such as DSO, Order-to-Invoice time, lead times, blocks, rework and automation rates help reveal process weaknesses.
- AI can already support order entry, invoice verification, receivables matching, Collections and Dispute Management.
- Successful Order-to-Cash process optimisation starts with analysing the complete end-to-end process rather than implementing an isolated tool.
Table of Contents
- Order-to-Cash Process Definition: What Is Order-to-Cash?
- Why Is the Order-to-Cash Process So Important?
- What Is the Difference Between Order-to-Cash, Quote-to-Cash and Procure-to-Pay?
- Order-to-Cash Process Steps: Which Phases Does O2C Include?
- SAP Order-to-Cash Process: How Does O2C Work in SAP S/4HANA?
- Order-to-Cash Process Example: From Customer Order to Payment
- What Role Does E-Invoicing Play in the Order-to-Cash Process?
- Digitalising the Order-to-Cash Process: What Does It Actually Mean?
- Automating the Order-to-Cash Process: Where Is the Greatest Potential?
- How Can AI and Automation Improve the Order-to-Cash Process?
- What Are the Benefits of an Optimised Order-to-Cash Process?
- What Challenges and Sources of Error Exist in the Order-to-Cash Process?
- Which KPIs Are Suitable for the Order-to-Cash Process?
- Optimising the Order-to-Cash Process: Where Should Companies Start?
- Best Practices for the Order-to-Cash Process
- Do's & Don'ts for the Order-to-Cash Process
- Step by Step: Digitalising and Automating the Order-to-Cash Process
- Conclusion – Why Organisations Should Optimise the Order-to-Cash Process
- Frequently Asked Questions About the Order-to-Cash Process
Order-to-Cash Process Definition: What Is Order-to-Cash?
The Order-to-Cash process definition can be summarised simply:
Order-to-Cash describes the end-to-end business process from the receipt of a customer order through to the receipt and posting of the corresponding payment.
Zuora also describes O2C as the end-to-end process from the customer placing an order to receiving payment and identifies order entry, order fulfilment, invoicing, payment processing and receivables management as key components.
From the organisation’s perspective, it is therefore a central revenue process. While the procurement side involves purchasing goods and services and subsequently paying suppliers, the Order-to-Cash process follows the opposite direction: The company sells a product or service and aims to convert that transaction into payment as reliably and quickly as possible.
Ecosio similarly describes O2C from the supplier’s perspective as the process from receiving a customer order to settlement of the outstanding receivable. In EDI-oriented scenarios, documents such as the purchase order, order confirmation, despatch advice, invoice and remittance advice can also be exchanged electronically.
Why Is the Order-to-Cash Process So Important?
Numerous process steps take place between a booked order and actual available liquidity. Any delay within this chain can postpone payment receipt.
For example, if an order is blocked due to missing master data, delivery may not be possible. If delivery information is missing or a billing block exists, the invoice may be created late. An incorrect invoice can subsequently trigger a dispute. If the payment reference is incomplete, Finance may have to allocate the incoming payment manually.
The Order-to-Cash process therefore has a direct impact on cash flow, working capital, process costs and customer experience.
IBM identifies improved cash flow, reduced revenue leakage, lower operational costs and higher customer satisfaction as some of the main benefits of O2C optimisation. Automation plays a particularly important role because it can reduce manual data entry and errors between individual process steps.
What Is the Difference Between Order-to-Cash, Quote-to-Cash and Procure-to-Pay?
These terms are often confused.
| Process | Start | End | Perspective |
|---|---|---|---|
| Quote-to-Cash | Quotation / Opportunity | Payment | Extended sales process |
| Order-to-Cash | Customer order | Payment | Sales and accounts receivable process |
| Procure-to-Pay | Procurement requirement / Purchase order | Supplier payment | Purchasing and accounts payable process |
Quote-to-Cash starts earlier than O2C. It typically includes quotation creation, pricing, negotiations and contract conclusion. Once these activities result in a customer order, the Order-to-Cash process begins in the narrower sense.
Procure-to-Pay or Purchase-to-Pay, by contrast, represents the purchasing side. Ecosio describes P2P as the process from purchase order to settlement of supplier liabilities and O2C as its counterpart on the sales side.
This distinction is also important when assessing SAP solutions. OpenText Vendor Invoice Management, for example, focuses on incoming invoices and therefore primarily on the Procure-to-Pay process rather than on the customer invoicing process within O2C.
Further information: SAP Invoice Management by OpenText
Order-to-Cash Process Steps: Which Phases Does O2C Include?
The number of Order-to-Cash process steps varies depending on the organisation and business model. IBM, for example, uses eight core steps. For an SAP-oriented end-to-end process, the following structure is practical.
Step 1 – Capture the Customer Order
The Order-to-Cash process begins with a binding customer order.
This order may originate from different channels, such as a CRM system, e-commerce solution, EDI, customer portal or manual order entry.
The order contains information including the customer, products or services, quantities, prices, delivery dates, payment terms and other relevant details.
This first step is already critical for a high level of automation. Incorrect customer, pricing or material data often causes issues throughout the entire downstream process.
Step 2 – Validate the Order and Credit Status
Depending on the business model, checks are performed for availability, completeness, pricing and credit risk.
SAP S/4HANA can, for example, include credit information in the sales order. If SAP Credit Management is active, users can view credit limit utilisation, while credit checks can also be applied to sales documents.
This allows companies to identify risks before goods are delivered or services are provided.
Step 3 – Fulfil the Order
Once the checks have been completed successfully, the actual order fulfilment takes place.
Depending on the business model, this may involve picking and packing goods, providing a service or delivering professional services.
This stage connects Sales with Warehouse Management, Logistics, Production or Service.
Step 4 – Delivery and Goods Issue
For physical products, the delivery process follows.
SAP Best Practice processes, for example, show the sequence from the sales order and, where applicable, credit release to creation of the outbound delivery and posting of the goods issue.
Goods issue is not merely a logistics event. It also generates financial and inventory-related impacts and frequently forms the basis for subsequent billing.
Step 5 – Billing and Invoice Creation
Once the billing-relevant prerequisites have been met, the customer invoice is created.
SAP Sales Billing supports automated and specialised billing processes. Once a billing document has been created, it can be transferred to Financial Accounting and provided through different output channels.
This is precisely the point at which e-invoicing is becoming increasingly important for many organisations.
Step 6 – Post and Manage the Receivable
The invoice creates a receivable from the customer.
SAP Receivables Management brings together functions including Accounts Receivable Accounting, Collections Management, Credit Management and Dispute Management.
Finance then monitors open items, due dates and potential disputes.
Step 7 – Receive and Allocate the Payment
When payment is received, it must be assigned to the correct invoice or open item.
For Accounts Receivable, SAP supports processes including the processing of incoming bank statements and automatic matching against open invoices. Payments that cannot be clearly allocated can subsequently be processed manually.
Step 8 – Reporting and Continuous Optimisation
Operationally, the Order-to-Cash process does not end with payment.
Organisations should subsequently analyse how long individual process stages take, where blocks occur, how much manual rework is required and which customers regularly pay late.
SAP provides tools such as the Order-to-Cash Performance app and SAP Signavio accelerators for this purpose.
SAP Order-to-Cash Process: How Does O2C Work in SAP S/4HANA?
An SAP Order-to-Cash process is neither a single module nor an isolated application. Instead, it results from the interaction of different functions within SAP S/4HANA and, where appropriate, complementary SAP solutions.
A typical process chain may look like this:
Sales Order → Credit Check → Availability Check → Outbound Delivery → Goods Issue → Billing → FI-AR → Incoming Payment → Clearing
SAP documents current S/4HANA Cloud processes covering, for example, sales order creation and processing, credit information, delivery and billing blocks, as well as delivery and invoicing data directly within the Sales process.
Several interconnected documents are created along this chain. This document flow is one of the key strengths of an integrated ERP system: Changes and statuses can be traced from the sales order through to billing.
Sales
Sales manages customer orders, prices, quantities, delivery conditions and other commercial information.
Logistics and Fulfilment
Delivery connects the customer order with warehouse and shipping processes.
Billing
Billing creates the documents required for invoicing and establishes the connection to Financial Accounting. SAP explicitly positions Sales Billing as a function that helps optimise the Order-to-Cash process and reduce billing errors.
Accounts Receivable
After billing, the sales process transitions into a receivables process. Open items, incoming payments, dunning, Collections and Disputes must be managed.
The SAP Order-to-Cash process therefore connects operational sales and logistics processes with Finance.
Order-to-Cash Process Example: From Customer Order to Payment
A simple Order-to-Cash process example illustrates the relationships.
An industrial customer orders 100 components.
The order is transmitted electronically to the supplier and created as a sales order in SAP. The system checks prices, availability and credit status. The delivery is then generated, the goods are picked and goods issue is posted.
Based on the delivery, the billing document is created. This generates the customer receivable in Finance. At the same time, a structured e-invoice is created and sent to the customer through the designated channel.
A few days later, the customer transfers the invoice amount. The electronic bank statement is processed and the payment is allocated to the open item. The item is cleared.
In a largely automated Order-to-Cash process, manual intervention is mainly required for exceptions—for example credit limit issues, delivery discrepancies, invoice corrections, disputes or payments that cannot be clearly assigned.
EDI can further automate this process. Ecosio describes, for example, a chain consisting of ORDERS for the purchase order, ORDRSP for the order confirmation, DESADV for the despatch advice, INVOIC for the invoice and REMADV for payment information.
What Role Does E-Invoicing Play in the Order-to-Cash Process?
Within O2C, e-invoicing affects the outbound invoicing side.
While traditional invoices are transmitted as paper documents or PDFs, structured e-invoices enable automated electronic processing.
This is particularly relevant for German B2B transactions: Since 1 January 2025, domestic companies have generally been required to be able to receive e-invoices. Transitional rules apply to invoice issuance: Until the end of 2026, other types of invoices can generally still be used; under the statutory requirements, invoice issuers with prior-year revenue of up to EUR 800,000 can benefit from a further transition period until the end of 2027.
For the Order-to-Cash process, this means that billing and e-invoicing should not be planned separately.
SAP Document and Reporting Compliance
SAP Document and Reporting Compliance supports the creation, processing and monitoring of electronic documents and statutory reports. SAP explicitly documents electronic customer invoices as part of this scope.
A typical target architecture may therefore look as follows:
SAP Billing Document → eDocument → Validation/Transformation → Legally Required Channel → Recipient → Status Response
Further information: SAP Document and Reporting Compliance
Further information: E-Invoicing with SAP
Peppol and Structured Formats
In international or national e-invoicing scenarios, networks and standards such as Peppol as well as UBL-based formats may become relevant.
Related Fink IT-Solutions articles:
PEPPOL SAP – Standard, Network or Part of the Solution?
Digitalising the Order-to-Cash Process: What Does It Actually Mean?
Organisations looking to digitalise the Order-to-Cash process should not simply replace paper documents with digital files.
A digital process is characterised by information flowing between the systems involved with as few media disruptions as possible.
For example:
An order is received electronically, automatically created in SAP, validated and released. Delivery statuses are forwarded automatically. Billing is system-supported. The e-invoice is transmitted electronically. Incoming payment information is imported from the bank statement and automatically allocated to the open item.
IBM emphasises that gaps between individual O2C steps frequently cause revenue leakage and errors. Integrating CRM, ERP, warehouse systems and payment solutions is therefore a key lever.
To digitalise the Order-to-Cash process means above all:
Capture data once, reuse it across systems and make process statuses continuously available.
Automating the Order-to-Cash Process: Where Is the Greatest Potential?
The Order-to-Cash process is well suited to automation because many steps follow recurring rules.
Stripe identifies order entry, credit checks, invoice creation and payment reminders as typical areas for automation and recommends first mapping the complete process and defining measurable objectives.
Automated Order Entry
Structured EDI orders, portals or integrated e-commerce processes can reduce manual order entry.
Automated Credit and Availability Checks
SAP can check sales documents against defined credit rules and manage delivery or billing blocks.
Automated Billing
Billing jobs and events can automate invoice creation once the relevant business prerequisites have been met.
Automated E-Invoicing
In supported country and process scenarios, SAP DRC can generate an electronic document from the outbound document and support regulatory transmission.
Automated Cash Application
SAP Cash Application uses machine learning to match incoming payments with open receivables. SAP describes the solution as automating receivables matching based on payment information and open invoices.
This makes it possible to automate the Order-to-Cash process without handing every decision entirely over to the system. Exceptions can still be escalated to employees in a controlled manner.
How Can AI and Automation Improve the Order-to-Cash Process?
In 2026, AI is evolving from individual forecasting capabilities towards agent-based process support.
SAP positions, for example, an Accounts Receivable Assistant for Collections, Dispute Management and a consolidated view of customer accounts. The approach introduced in May 2026 is intended, among other things, to prioritise overdue receivables, prepare customer communications and support dispute cases.
For recurring revenue models, SAP also describes the Recurring Receivables Assistant introduced in July 2026. It addresses Billing, Collections, Disputes and Receivables in high-volume O2C scenarios.
SAP also refers to a Sales Operations Assistant designed to support the creation of sales orders from unstructured data and the handling of fulfilment issues. Depending on the product, release and availability status, individual assistants and agents may be generally available, in Early Access or still planned.
This creates several AI opportunities for organisations:
Order Entry: Identify information in unstructured customer enquiries and convert it into order data.
Credit and Risk: Improve the assessment of risk and payment probability.
Billing: Detect anomalies and errors before invoices are sent.
Collections: Prioritise receivables based on risk and expected payment probability.
Dispute Management: Understand customer complaints, consolidate information and propose next steps.
Cash Application: Automatically match incoming payments with open items.
This does not mean that the Order-to-Cash process becomes fully “autonomous”. A realistic development path moves from rule-based automation through AI-supported recommendations towards agents capable of executing controlled actions.
What Are the Benefits of an Optimised Order-to-Cash Process?
A professionally designed O2C process has a positive impact on several areas of the organisation at the same time.
Faster Cash Flow
The shorter the period from order through billing to payment, the faster liquidity becomes available to the organisation.
Fewer Errors
Automated data transfer reduces manual entry errors, incorrect pricing and inconsistent information.
Greater Transparency
End-to-end status information makes it visible where orders, deliveries, invoices or payments are blocked.
Better Customer Experience
Accurate order confirmations, on-time deliveries, correct invoices and transparent communication reduce customer enquiries and complaints.
Lower Process Costs
Fewer manual activities and less rework reduce operational costs.
Better Scalability
A standardised Order-to-Cash process can handle growing order volumes more effectively than a heavily manual process.
What Challenges and Sources of Error Exist in the Order-to-Cash Process?
Many O2C problems do not originate within a single system, but at the handovers between different departments.
Typical causes include:
poor customer or material master data, inconsistent pricing logic, manual order entry, credit or delivery blocks, lack of availability, incorrect invoices, delayed invoice creation, missing e-invoicing information, dispute cases and payments that cannot be allocated.
SAP’s own Order-to-Cash Performance app therefore examines, for example, delivery and billing blocks, changes to critical fields and lead times.
A common strategic mistake is to optimise only individual areas.
If, for example, invoice creation is automated while sales orders are still entered incorrectly, the underlying problem is simply shifted further downstream.
The Order-to-Cash process should therefore always be viewed end to end.
Which KPIs Are Suitable for the Order-to-Cash Process?
You can only optimise the Order-to-Cash process if progress can be measured.
SAP Signavio provides O2C analyses covering areas such as lead times, automation rates, customer satisfaction, rework, working capital and additional optimisation potential.
Relevant KPIs include:
| KPI | What It Measures |
|---|---|
| Days Sales Outstanding (DSO) | Average time until payment is received |
| Order-to-Invoice Time | Time between customer order and invoicing |
| Order-to-Delivery Time | Time between order and delivery |
| Goods-Issue-to-Billing Time | Time between goods issue and billing |
| Billing Error Rate | Proportion of incorrect invoices |
| Rework Rate | Proportion of transactions requiring rework |
| Credit Block Rate | Proportion of credit-blocked orders |
| Billing Block Rate | Proportion of transactions blocked for billing |
| Automation Rate | Proportion of automatically processed steps |
| Payment Matching Rate | Proportion of payments matched automatically |
| Dispute Resolution Time | Time required to resolve invoice disputes |
| Electronic Invoice Rate | Proportion of structured electronic outbound invoices |
SAP explicitly uses “Order to Invoice” and other lead-time metrics in its O2C performance analysis.
Stripe also identifies DSO and payment trends as relevant KPIs for O2C dashboards.
Optimising the Order-to-Cash Process: Where Should Companies Start?
Organisations looking to optimise the Order-to-Cash process should not immediately start by replacing software.
The first step should be to make the actual as-is process visible.
Map the End-to-End Process
Document the complete journey from customer order to payment clearing, including all systems, roles, approvals and manual activities.
Measure Bottlenecks
Analyse where waiting times, blocks, rework and disputes occur.
Address Root Causes Rather Than Symptoms
A high number of invoice corrections may, for example, be caused by incorrect order data. In that case, optimising Billing alone is not enough.
Use Standards
Use existing SAP standard processes and interfaces before developing custom extensions.
Integrate E-Invoicing
Treat statutory e-invoicing requirements as part of the Billing process rather than as a downstream file conversion activity.
Apply Automation Selectively
Start by automating repetitive, rule-based and high-volume activities.
Establish Process Monitoring
The process must be monitored continuously after go-live.
SAP Signavio provides O2C-specific dashboards and Value Accelerators for SAP S/4HANA and SAP ECC.
Best Practices for the Order-to-Cash Process
Treat Master Data as the Foundation of the Process
Customer master data, payment terms, prices, tax data and product information must be maintained consistently.
Avoid Media Disruptions
Data should not be transferred repeatedly between email, Excel, CRM and ERP systems.
Create Correct Invoices as Early as Possible
Every unnecessary delay between delivery and billing also postpones potential payment receipt.
Analyse Disputes Systematically
Recurring complaints are often an indication of upstream process problems.
Manage Finance and Sales Together
O2C is neither exclusively a Sales process nor exclusively a Finance process.
Use Human-in-the-Loop for Exceptions
Automation should handle standard cases. Complex risks and exceptions still require business decisions.
Do’s & Don’ts for the Order-to-Cash Process
Do
Consider the entire end-to-end process. Define shared KPIs for Sales, Logistics and Finance. Use structured data, integrated SAP processes and standardised interfaces. Integrate e-invoicing and compliance directly into Billing and regularly measure lead times and automation rates.
Don’t
Do not optimise isolated transactions only. Do not automate faulty processes without improving them first. Do not treat e-invoicing as an isolated Finance project. Do not ignore the root causes of credit, delivery and billing blocks. And do not evaluate AI based on the number of agents deployed, but on measurable business value.
Step by Step: Digitalising and Automating the Order-to-Cash Process
Step 1 – Define the Scope
Define legal entities, sales channels, customer groups, countries and relevant business models.
Step 2 – Map the Current Process
Document all Order-to-Cash process steps, systems and interfaces.
Step 3 – Establish KPIs
Measure metrics such as DSO, Order-to-Invoice time, billing blocks, rework and automation rates.
Step 4 – Analyse Root Causes
Distinguish between process, data, system and organisational problems.
Step 5 – Define the Target Process
Determine which steps can be standardised, automated or eliminated entirely.
Step 6 – Define the SAP Architecture
Assess SAP S/4HANA Sales, Finance, Credit Management, Receivables Management, Integration, SAP DRC and, where appropriate, SAP Signavio.
Step 7 – Integrate E-Invoicing
Define formats, country requirements, transmission channels and status processing.
Step 8 – Implement Automation
Begin with high-volume standard cases and establish controlled exception processes.
Step 9 – Run a Pilot
Test the process using real business scenarios—including blocks, corrections and disputes.
Step 10 – Continuously Improve
An Order-to-Cash process is not a one-time implementation project. Process volumes, legal requirements, systems and customer behaviour change continuously.
Conclusion – Why Organisations Should Optimise the Order-to-Cash Process
The Order-to-Cash process is one of the most important value-creating processes within an organisation because it connects sales activity with actual cash flow.
Its quality does not depend only on how quickly a customer order is created. The decisive factor is the interaction between order entry, credit checks, fulfilment, delivery, billing, e-invoicing, receivables management and payment clearing.
A modern SAP Order-to-Cash process uses the integrated capabilities of SAP S/4HANA and connects Sales, Logistics and Finance end to end. Complementary solutions such as SAP Document and Reporting Compliance can address regulatory e-invoicing requirements, SAP Signavio supports process analysis and optimisation, while SAP Cash Application and current AI assistants can further automate selected Finance processes.
Organisations that want to digitalise the Order-to-Cash process should therefore not begin with a single technology. Processes, data and responsibilities must first be clearly defined.
Building on this foundation, companies can automate the Order-to-Cash process—initially through rule-based workflows and increasingly through AI-supported analysis and controlled Agentic AI.
The objective remains the same:
Fulfil orders correctly, create invoices quickly and accurately, manage outstanding receivables transparently and convert revenue into liquidity as efficiently as possible.
Frequently Asked Questions About the Order-to-Cash Process
What Is the Order-to-Cash Process and How Does It Work?
The Order-to-Cash process covers the business activities from receipt of a customer order through to payment receipt and financial posting. Typical steps include order entry, credit checks, fulfilment, delivery, invoicing, receivables management and payment clearing.
Which Steps Does the Order-to-Cash Process Include?
The exact Order-to-Cash process steps differ depending on the business model. Typical stages include the customer order, credit checks, fulfilment, delivery, billing, Accounts Receivable, payment receipt and reporting.
How Does the Order-to-Cash Process Work in SAP S/4HANA?
The SAP Order-to-Cash process connects Sales, Fulfilment, Billing and Finance in particular. After credit and availability checks, a customer order can lead to delivery and goods issue. A billing document is then created and transferred to Accounts Receivable.
How Can the Order-to-Cash Process Be Automated?
Organisations can automate areas including order entry, validation, credit checks, Billing, e-invoicing, Collections and Payment Matching. Clean data and integrated systems are essential prerequisites.
What Is the Difference Between Order-to-Cash and Procure-to-Pay?
O2C focuses on selling to customers and subsequently receiving payment. Procure-to-Pay focuses on purchasing from suppliers and subsequently paying those suppliers.
What Role Does E-Invoicing Play in the Order-to-Cash Process?
E-invoicing is part of the Billing and outbound invoicing process. Structured invoice data can be generated, validated and transmitted automatically through required channels. SAP DRC supports electronic documents within the relevant supported country and process scenarios.
How Can Organisations Optimise Their Order-to-Cash Process?
Organisations should analyse lead times, blocks, errors and rework, improve master data, reduce media disruptions, expand automation selectively and establish shared KPIs across Sales, Logistics and Finance.
What Challenges Exist in the Order-to-Cash Process?
Typical challenges include incorrect master data, manual order entry, lack of availability, credit and billing blocks, delayed invoicing, disputes and payments that cannot be clearly allocated.