How to Forecast Cash Receipts from Sales

A sales forecast tells you what a business expects to sell. A cash receipts forecast tells you when that money will actually arrive in the bank. These two numbers are rarely the same — and the gap between them is where cash flow problems live.

This post is the second part of a two-part series on forecasting. The first part covered how to forecast sales: what drives revenue, which forecasting methods exist, and how to challenge the numbers from management. This part covers the next step — converting those sales into a reliable week-by-week cash receipts forecast.

For the first few weeks of any 13-week cash flow forecast, the task is relatively straightforward: review the accounts receivable ledger, assess which invoices are likely to be paid and when, and build the receipts schedule from there. But further out, the forecaster must also estimate when future sales will generate cash. That requires understanding how different types of sales convert into bank deposits — and how long the process takes.

Revenue and cash are not the same thing

Before building a receipts forecast, it is important to understand why sales and cash receipts are different numbers recorded at different times.

Revenue recognition follows accounting rules. Revenue is recorded when goods are delivered or a service is performed — regardless of whether any money has been received. This is the accrual principle.

Cash collection follows a different logic entirely. It records when money actually arrives in the bank account. This is what matters for a cash flow forecast.

The gap between these two events can be days, weeks, or months depending on how the business operates. Here are three common patterns:

Why are they different?

Accrual accounting records revenue when earned, regardless of payment. A consulting firm completes a project in March and invoices the client. Revenue appears in March. But the client pays in May. The P&L looks fine. The bank account does not.

Deferred revenue is the opposite problem. A SaaS company receives 12 months of subscription fees in January. Cash arrives in January. But revenue is recognised monthly across the year. The bank account looks fine. The P&L spreads the income.

Unearned revenue is similar. A customer pays a deposit before work begins. The cash is received immediately. But revenue cannot be recognised until the work is done.

Trade receivables (accounts receivable) represent revenue recognised but not yet collected. This is the most common gap in credit-sale businesses. Every invoice sitting unpaid on the receivables ledger is revenue that has been recognised but has not yet become cash.

Contract assets arise in project businesses. A construction company may complete 40% of a project but not yet be entitled to invoice. The work is done. The revenue may be partially recognised. But no cash has moved and no invoice has been raised yet.

Cash-to-revenue timelines

Understanding which pattern applies to each part of the business is the starting point for any receipts forecast.

Credit sales (most B2B businesses)

Actual collection may occur before or after the contractual due date, depending on customer payment behaviour.

Subscription sales — advance billing

Here cash arrives before revenue is earned. The opposite of the credit sale situation.

Project sales with retention

Retention is commonly released only after final project acceptance, often several months after the main invoice has been paid.

Starting with existing receivables

The most reliable part of any receipts forecast comes from invoices that have already been raised. These exist on the accounts receivable ledger right now. The forecaster does not need to estimate whether the sales will happen — they already have. The only question is when the cash will arrive.

The forecaster reviews the full receivables ledger and, for each outstanding invoice, asks:

• When is this invoice due based on agreed payment terms?
• Does this customer typically pay on time, early, or late?
• Are there any known reasons to expect delay — a dispute, financial difficulty at the customer, or a seasonal slowdown?

The answers to these questions determine when each invoice is expected to convert into cash. This forms the first and most reliable layer of the 13-week receipts forecast.

Customer payment behaviour

Payment terms state when an invoice should be paid. Payment behaviour describes when customers actually pay. These are rarely the same.

Some customers pay early. Many pay a few days late. Some pay weeks or months after the due date. A receipts forecast built purely on payment terms — assuming every invoice will be paid exactly on its due date — will consistently overstate cash inflows.

The forecaster builds a payment behaviour database by analysing historical receipts. For each customer, the average number of days between invoice date and actual payment date is calculated and compared against the agreed terms.

Customer C is a particular concern. The agreed terms are 60 days, but the actual average is 92 days — a gap of a full month. If the business is forecasting cash from Customer C based on agreed terms, it will consistently show cash arriving 32 days earlier than it actually does.

Once built, this database replaces the question "when is this invoice due?" with a more useful question: "when does this customer actually pay?"

Collection curves

For businesses with many customers — where tracking each customer individually is not practical — a collection curve provides a faster and equally useful tool.

A collection curve shows what percentage of a given period's invoices has been collected at each point in time after the invoice date. The forecaster builds this curve by taking all invoices raised in a historical period and tracking when the money actually arrived.

This curve tells the forecaster that if €1,000,000 of invoices are issued in a given week, approximately €200,000 will arrive within the first week, €350,000 within two weeks, and so on. The forecaster applies this pattern to the sales forecast to estimate when the cash will arrive — without needing to analyse every individual invoice.

Different customer groups often have very different collection curves. It is worth building separate curves for:

• Large strategic customers — often have their own payment systems and timelines.
• Small and medium customers — behaviour varies more widely.
• Public sector customers — often pay more slowly due to internal approval processes.
• International customers — additional delays from cross-border banking and currency conversion.

Receipts by sales channel

Different sales channels convert revenue into cash at different speeds and in different ways. The forecaster needs to understand each channel separately before building a receipts schedule.

Retail sales

Cash transactions settle instantly. Card transactions go through a payment processor, which holds the funds for a period before transferring them to the business bank account. The settlement delay is typically one to three business days, depending on the processor and the bank.

The forecaster identifies the actual split between payment methods and the settlement terms for each processor used by the business.

E-commerce sales

The customer pays at checkout, but the cash does not arrive in the business’s bank account immediately. Payment processors and marketplaces hold the funds for a period before transferring them, creating a timing gap between recorded sales and actual cash inflow.

Stripe typically transfers funds on a rolling basis for established accounts, though the exact timing depends on account history, risk assessment, and current policies. New accounts often face longer initial holds while the processor evaluates risk.

PayPal generally releases funds within a few business days on standard accounts. However, unusual activity, high volumes, or disputes can result in significantly longer holds.

Amazon Marketplace disburses funds on a scheduled cycle after deducting fees, returns reserves, and any outstanding balances. This means a sale made today can take multiple weeks before the net amount reaches your bank account.

Refunds further reduce the actual cash received. Forecasters typically estimate a refund rate based on historical data and deduct it from the gross receipts forecast to better reflect realistic cash inflows.

For example:

B2B credit sales

The sale is made today. The cash may arrive weeks or months later — if it arrives at all.

Standard payment terms in most European markets are 30 days. But in practice, terms vary: 14 days for small suppliers, 60 or 90 days for large corporate buyers, and sometimes longer in certain industries or countries. Agreed terms and actual payment behaviour, as discussed above, are rarely the same.

Bad debt risk adds a further complication. A small percentage of B2B invoices are never paid. The forecaster handles this in two ways:

• A specific provision excludes or delays payment of a specific invoice if there is a known risk — for example, a customer that has entered administration or has not responded to payment requests.
• A general provision applies a percentage reduction to total receivables based on the business's historical bad debt rate — for example, 1.5% of all B2B receivables written off each year on average.

Subscription businesses

Subscription cash flows are among the most predictable of any model — the number of active subscribers and the monthly fee are both known in advance. But predictable does not mean certain.

Churn rate — the percentage of subscribers who cancel each month — reduces the subscriber base over time. Monthly churn of 3% compounds across 13 weeks, and the forecaster must apply it week by week rather than assuming a flat subscriber count throughout the period.

Billing timing also matters. A subscription billed on the first of each month produces a large cash spike at the start of the month and near-zero subscription receipts for the remaining weeks. This pattern must be reflected in the weekly forecast — not smoothed across all weeks equally.

Project businesses

Project cash flows are the most irregular of any model. Revenue does not arrive evenly — it comes in large amounts at specific points tied to project milestones.

Retention adds a further delay. Most construction and engineering contracts allow the client to withhold 5–10% of each invoice until the project is fully complete and any defects are resolved. This retention may be held for months or over a year after practical completion. The forecaster must track all retention balances separately and include expected release dates in the receipts forecast.

DSO analysis

Days Sales Outstanding (DSO) is a single number that summarises how long, on average, a business takes to collect cash after making a sale.

The formula is:

Example: a business has €2,000,000 in outstanding receivables and annual revenue of €12,000,000.

DSO = (2,000,000 ÷ 12,000,000) × 365 = 61 days

If the agreed payment terms are 30 days, a DSO of 61 days means the business is waiting twice as long as it should to collect cash.

More useful than a single DSO figure is a DSO trend. A rising DSO — even if sales are stable — means cash is arriving progressively later. The 13-week forecast must reflect this deterioration, not assume a return to earlier, healthier levels.

Accounts receivable aging

DSO gives an overall picture. An accounts receivable aging report gives the detail behind it.

An aging report lists every unpaid invoice and groups them by how long they have been outstanding. This makes it possible to see at a glance which invoices are current, which are overdue, and which represent a potential bad debt.

Customer A is paying normally. Customer B is slightly slow but not alarming. Customer C has invoices spread across multiple aging buckets — a clear sign of a deteriorating payer. Customer D has nothing current and significant amounts in the oldest buckets — a likely bad debt situation.

The forecaster uses the aging report in two ways: first, to estimate when each existing invoice will actually be paid based on visible payment patterns rather than due dates; second, to identify customers whose behaviour is worsening so that their expected receipts can be delayed or reduced in the forecast.

Customer concentration risk

Most businesses collect a disproportionate share of their revenue from a small number of customers. This is called customer concentration risk, and it has direct consequences for cash flow forecasting.

Customer rank in the table below shows the customers ordered by size — Rank 1 is the largest customer, Rank 2 the second largest, and so on. The table groups smaller customers (ranks 4–10 and all others) for readability.

In this example, the top three customers represent 54% of all receipts. If the largest customer delays payment by 30 days, the business loses approximately €267,000 of expected cash that month. If that customer were to default entirely, the impact would be immediate and severe.

The forecaster models customer concentration as a specific risk scenario. For each of the largest customers, the forecaster asks: what happens to the weekly cash forecast if this customer pays 30 days late? What if they do not pay at all?

Businesses with high concentration risk should monitor the financial health of their largest customers actively. A payment delay is often the first visible signal of financial difficulty at the customer — and it is better to notice it in the forecast than to discover it when the cash does not arrive.

Stress testing the receipts forecast

A single-point forecast — one set of numbers representing the most likely outcome — is not sufficient for a well-prepared 13-week cash flow. The forecaster must also test what happens when things go wrong.

Stress testing applies specific adverse scenarios to the base forecast and shows the resulting cash impact week by week.

Scenario 1 — sales are 10% lower than forecast

The forecaster reduces the sales forecast by 10% and recalculates receipts. This shows which weeks are most affected and by how much.

Scenario 2 — collections are 15 days slower

Every expected receipt is shifted forward by 15 days. A receipt expected in week 3 moves to week 5. This shows the impact of a general slowdown in customer payments — common during economic downturns when customers across the board begin stretching payment terms.

Scenario 3 — largest customer defaults

All expected receipts from the largest customer are removed entirely. This is the most severe scenario. It tests whether the business can survive the complete loss of its biggest revenue source within the 13-week window.

Receipts in scenario shows the total cash the business would still collect if that scenario occurs. The Shortfall column shows how much less cash would be received compared to the original forecast.

Stress testing does not predict which scenario will occur. Its purpose is to identify the point at which the business would face a liquidity problem — and to make that visible before the crisis happens, not after.

Putting it all together — the sales-to-cash model

The complete receipts forecast combines three layers of information.

Layer 1 — receipts from existing receivables

The most reliable layer. The invoices already exist. The forecaster applies customer-specific payment behaviour — or the collection curve — to estimate when each invoice will convert into cash within the 13-week window.

Layer 2 — receipts from forecast sales

For sales not yet invoiced, the forecaster applies the relevant collection pattern for each channel. A B2B credit sale with 30-day terms and a collection curve will generate cash receipts spread across weeks 2 through 8 or later. A retail card transaction will generate cash in 1–2 business days.

Example — Week 1 sales of €500,000, B2B credit customers, 30-day terms:

Layer 3 — judgement adjustments

The forecaster applies specific adjustments for known risks and unusual circumstances:

• A customer in financial difficulty — delay or remove their expected receipts
• A disputed invoice — exclude from the forecast until the dispute is resolved
• A seasonal slowdown in customer payments — apply a delay to the relevant period
• A large retention balance due for release — add to the forecast at the contractual release date

The combined output

Sales and receipts move in the same direction but never at the same time and never in the same amounts. The difference column shows the cash that has been earned but not yet received — money that exists on the balance sheet as a receivable but has not yet reached the bank account. This gap is what the 13-week cash flow forecast exists to measure and manage.