Debtor days estimate how long, on average, customers take to pay: trade debtors divided by credit sales, multiplied by 365. The figure is only meaningful if the debtors and sales are on the same VAT basis and the year end balance is representative, so seasonal and VAT registered businesses need to adjust it before comparing.

How do you calculate debtor days?

ACCA gives the receivables collection period as receivables ÷ credit sales × 365 days. Its financial statements interpretation article uses trade receivables and allows revenue to be used where the credit sales figure is not available. In UK accounts the receivables line is “Trade debtors” under current assets, and credit sales come from turnover less any cash or card sales that were never on credit.

Three choices change the answer:

  • Closing or average debtors. Average debtors (opening plus closing, divided by two, or better a monthly average) smooth out a single unusual year end. ACCA notes that exam questions often have to assume year end receivables are representative, which is an assumption, not a fact.
  • 365 or another period. ACCA notes exam questions sometimes use 360 days. For monthly management reporting, use the number of days in the period and the sales for that period.
  • Trade debtors only. Other debtors, prepayments, amounts owed by group companies and director’s loan balances are not customer debt and should be left out.

ACCA’s interpretation guidance says an increase could indicate deteriorating credit control or potential bad debts, while a fall could reflect better credit control or settlement discounts. Some businesses deliberately offer long credit to win sales, so the number has to be read against the terms the business actually offers.

Why does VAT distort debtor days?

For a VAT registered business the sales invoice includes VAT, so the trade debtors balance includes VAT. Turnover does not. Section 474 of the Companies Act 2006 defines turnover as amounts derived from goods and services after deduction of trade discounts, VAT and other taxes based on those amounts. Dividing a VAT inclusive debtor balance by VAT exclusive sales overstates debtor days.

Illustration only. Annual sales are £1,200,000 before VAT, all at the 20% standard rate. Trade debtors at the year end are £180,000 including VAT.

Method Calculation Debtor days
Unadjusted 180,000 ÷ 1,200,000 × 365 54.8
Debtors stripped of VAT (180,000 ÷ 1.2) ÷ 1,200,000 × 365 45.6
Sales grossed up for VAT 180,000 ÷ 1,440,000 × 365 45.6

The unadjusted figure adds more than nine days that have nothing to do with how fast customers pay. Either adjustment gives the same answer. The complication is a mixed business: exports, zero rated and exempt sales carry no VAT, and the reduced rate is 5%, so a single 1.2 divisor is wrong. Where the sales mix varies, work from the sales ledger, which records gross invoice values, rather than from the accounts.

How does seasonality distort the figure, and what is the count back method?

The simple formula assumes sales are spread evenly across the year. If a business makes most of its sales in the final quarter, year end debtors are high relative to annual sales and debtor days look poor even when customers pay on time. A business whose quiet season falls at the year end looks better than it is.

The count back method fixes this by matching the debtor balance against the most recent months of sales. Illustration only. Year end debtors (VAT inclusive) are £150,000. Gross sales were £100,000 in December, £80,000 in November and £60,000 in October.

  • December’s £100,000 accounts for 31 days, leaving £50,000 of debtors.
  • November’s £80,000 covers 30 days. £50,000 ÷ £80,000 × 30 = 18.75 days.
  • Debtor days = 31 + 18.75 = about 50 days.

If the annual formula had been used with gross sales of £720,000 spread evenly, the answer would be 150,000 ÷ 720,000 × 365 = 76 days. The count back figure reflects what customers are actually doing now, which is why credit controllers prefer it for monthly reporting.

What else can make debtor days unreliable?

  • Factoring and invoice discounting. FRS 102 paragraph 11.33 allows a receivable to be derecognised only where the contractual rights expire or substantially all risks and rewards (or control) pass to another party. Under paragraph 11.34, if significant risks are retained the business keeps the debtor on the balance sheet and shows a liability for the cash received. With recourse arrangements therefore leave debtors in the ratio; non recourse factoring may remove them, which can make debtor days look far better than the underlying collection.
  • Cash sales in turnover. A retailer with some trade accounts will show tiny debtor days if all turnover is used. Use credit sales only.
  • Old debts not written off. Irrecoverable balances inflate the figure. See impairment of debtors for when a provision is required.
  • Abridged or filleted accounts. Under section 444(1) a small company must file its balance sheet and may choose whether to file its profit and loss account. Where an abridged profit and loss account is used, paragraph 1A(2) of Schedule 1 to SI 2008/409 combines turnover into a single gross profit line. Outsiders often cannot calculate debtor days at all from small company filings.

How can a business improve its debtor days?

ACCA’s accounts receivable guidance divides the work into assessing creditworthiness, setting terms and monitoring, and collecting cash. In practice:

  • Invoice quickly and accurately. ACCA notes that a late or inaccurate invoice is often used by customers as a reason to dispute and delay.
  • Set credit limits and watch the aged analysis. The aged debtors report shows which accounts are driving the figure.
  • Chase personally. ACCA observes that chasing calls to a senior contact often have more effect than statements and letters.
  • Use the late payment law. If no payment date is agreed, GOV.UK guidance says payment is late 30 days after the customer receives the invoice or the goods or service, if later. Agreed business to business terms should usually be within 60 days. Statutory interest is 8% plus the Bank of England base rate, and a fixed recovery sum of £40, £70 or £100 can be charged depending on the size of the debt.
  • Price settlement discounts carefully. ACCA’s worked example shows a 1% discount for payment in 10 days, when customers take 41 days, costs about 12.6% a year, more than an overdraft at 9%. Customers also tend to take the discount and still pay late.
  • Consider factoring. ACCA notes a factor may lend up to 80% of outstanding receivables, though fees can be high and customer relationships can suffer.

A business using the VAT cash accounting scheme does not pay output VAT until the customer pays, which eases the cash cost of slow debtors but does not change the debtor days figure.

How do debtor days fit with the other working capital ratios?

Debtor days are one of three components of the cash conversion cycle, alongside stock days and creditor days. ACCA’s working capital guidance stresses comparing trends over time and against sector benchmarks, while warning that sector averages may themselves reflect poor practice. A business paying suppliers in 30 days while customers take 60 is funding its customers out of its own cash or overdraft.

What mistakes come up most often?

  • Dividing VAT inclusive debtors by VAT exclusive turnover.
  • Using total turnover when a large share of sales is for cash.
  • Comparing a December year end retailer with a June year end one without allowing for the season.
  • Including other debtors, prepayments or group balances in the numerator.
  • Celebrating a fall caused by non recourse factoring rather than by customers paying faster.

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Sources

Reviewed by Christine Anderson, Broker, Solar Protect. Last reviewed 8 October 2026. Part of Accountapedia, the Solar Protect guide to UK tax and accounting. This page is general information, not personalised advice.