Get Paid Faster: A Growth-Stage Founder's Guide to Reducing Debtor Days

UK small businesses are currently owed around £26 billion in unpaid invoices at any one time. The average firm waits 29.3 days to be paid, and £22,000 sits in overdue invoices on the average small business balance sheet. Late payment is not a minor irritation. It is a leading cause of business failure, contributing to roughly 38 UK business closures every day.

If you are growing, this problem gets worse, not better. More customers, more invoices, and often bigger clients with more negotiating power all mean more cash tied up in work you have already delivered. This guide sets out why debtor days deserve your attention as a growth metric, what is changing in UK payment law during 2026, and the practical steps that reduce how long you wait to get paid.

Debtor days, sometimes called Aged Debtors (or Aged Receivables), measures the average number of days between raising an invoice and receiving payment. The formula is simple: divide your trade debtors by annual revenue, then multiply by 365.

Think of debtor days as the fuel line between your sales engine and your fuel tank. You can have a powerful engine, winning contract after contract, but if the fuel line is too long and too narrow, the tank runs dry regardless of how much fuel is technically on its way. A business can be profitable on paper and still run out of cash because too much of that profit is sitting unpaid in customer inboxes.

Tracking debtor days turns a vague worry ("cash feels tight") into a specific, manageable number you can act on.

Mature businesses tend to have stable customer bases, established credit control habits, and larger cash reserves to absorb delays. Growth-stage businesses rarely have all three.

This combination means a growing business can be doing everything right commercially and still face a genuine cash crisis, purely because the gap between delivering work and being paid for it has widened.

The data confirms this is a widespread, structural issue rather than something specific to any one business or sector.

If you recognise these numbers in your own business, you are far from alone. Understanding that this is a systemic problem, not a personal failing, matters because it means the fix is procedural, not a matter of trying harder.

On 24 March 2026, the UK government announced its toughest crackdown on late payment in over twenty-five years. Three changes are particularly relevant for growth-stage founders.

These reforms still need primary and secondary legislation, with the first measures expected in late 2026 or early 2027. In the meantime, the existing statutory right to claim interest and fixed compensation on late B2B invoices under the Late Payment of Commercial Debts (Interest) Act 1998 already applies, and it is underused by small businesses who are simply unaware they can invoke it.

Payment terms should be a condition of doing business, not a line item nobody reads. State them clearly in your proposal, your contract, and your invoice. Shorter terms, such as 14 or 21 days, are entirely reasonable to request, particularly with new customers who have not yet earned extended terms.

Every day between completing work and sending the invoice is a day added to your debtor days, regardless of how quickly the customer eventually pays. Invoice on the day work is delivered or the day a milestone is reached. Make sure each invoice includes a clear due date, itemised charges, and easy payment instructions. Ambiguity gives customers a reason to query, and a query is a delay.

Do not leave chasing to chance or to whoever has time that week. A simple cadence works well:

Consistency matters more than aggression. Customers pay the suppliers who chase reliably before they pay the ones who chase occasionally.

Before extending payment terms to a new client, a basic credit check takes minutes and can flag a business with a known pattern of late payment or financial distress. This is particularly worthwhile before large contracts, where a payment delay would have a material effect on your cash flow.

A small early payment discount, such as 2% for payment within seven days, can shift customer behaviour without a large cost to you. On the other side, make sure customers know that late payment interest under the 1998 Act, or your own contractual late fee, will actually be applied, not just referenced as a formality.

If debtor days are structurally long because of the nature of your industry or your customer base, invoice finance or factoring can release cash tied up in unpaid invoices, at a cost. This is a tool for managing a known, ongoing gap, not a substitute for fixing avoidable delays in your own process.

The businesses that make lasting progress on this problem do not treat it as a one-off clean-up exercise. They track debtor days weekly, alongside their cash flow forecast, so that a slippage is caught in week one rather than discovered in week eight when the cash gap has already caused a problem elsewhere.

A simple weekly dashboard should show your current debtor days figure, the total value of overdue invoices, and a short list of the customers most overdue. Reviewing this every week, even briefly, keeps chasing proactive rather than reactive, and gives you an early warning of any customer relationship that is starting to deteriorate.

Pick your three most overdue invoices right now and pick up the phone. Do not email. A short, direct conversation about an overdue invoice resolves more late payments in a week than a month of automated reminders, and it starts the habit of proactive chasing that reduces debtor days for good.

TLDR: Growth-stage UK businesses are owed £26 billion at any given time and wait nearly a month to get paid, so the post makes the case for treating debtor days as a growth KPI and gives six practical steps — tight payment terms, fast invoicing, a chasing cadence, credit checks, incentives, and invoice finance — to get paid faster.