The Senior Creditor: Funding the 31 January Tax Bill While Your Own Ledger Sits Unpaid

Ask any small supplier why the invoice has not been paid and the reply tends to follow a pattern: the customer is waiting on its own debtors, the finance director is away, the payment run has slipped to the next month. Those explanations carry weight in a commercial relationship. They carry none at all with HMRC.

When the self-assessment balancing payment for 2025-26 and the first payment on account for 2026-27 fall due on 31 January 2027, the Revenue will expect the money. The fact that two of your customers are sitting on 75-day terms and a third has gone quiet since October is, from HMRC's perspective, an irrelevance. It is worth saying plainly: your tax liability is your most senior creditor. It should be funded and treated as such, ahead of trade creditors and, in most months, ahead of your own drawings.

A creditor with statutory teeth

Trade creditors negotiate. HMRC does not. Late payment of tax attracts interest charged at the Bank of England base rate plus 2.5 percentage points, accruing daily from the due date, and the department has an armoury that no commercial supplier possesses: determinations where returns are missing, penalties that are separate from the underlying debt, collection through an adjustment to your PAYE code, and, in the last resort, enforcement agents or a direct recovery of funds from bank accounts.

The distinction that matters most for cash-flow planning is this: filing and paying are two separate obligations. If the money is short, the return should still be filed by 31 January. A late filing penalty of £100 is fixed and immediate, and it is added to a bill you already cannot pay. Filing on time while agreeing a payment arrangement keeps the problem to one dimension rather than two.

Ring-fence the money before it reaches the current account

Most suppliers who get into difficulty in January did not spend their tax money deliberately. They spent it in £400 instalments across November and December, because it was sitting in the same account as everything else.

The discipline that works is simple enough to describe and hard to sustain. Open a separate deposit account, ideally one that takes a day or two to access, and calculate the tax content of your income rather than the tax on your profit. A supplier on the cash basis can work from receipts: as each payment lands, move a fixed proportion, based on your effective rate plus a margin for Class 2 and Class 4 National Insurance, into the reserve on the same day. Payments on account already made in January and July reduce the balancing figure, so the reserve target is the difference, not the whole liability.

If the reserve is already behind, do not attempt to catch up in one go. Set a weekly transfer that you can actually sustain and diarise it. A reserve built from twelve small transfers in November and December is worth more than a good intention in January.

A December to January calendar

First half of December. Reconcile the sales ledger and identify every invoice more than 60 days old. Send statements, then telephone. Email is easily ignored; a call to the accounts payable clerk establishes whether an invoice is disputed, awaiting a purchase order number, or simply unprocessed. Disputes are the most common hidden cause of late payment and the cheapest to fix.

Second half of December. For larger debts, move to a formal letter before action, and quantify the statutory interest and compensation available under the Late Payment of Commercial Debts (Interest) Act 1998. Compensation is a fixed sum that scales with the invoice value, and claiming it is a legitimate part of the recovery conversation rather than an escalation.

Late December. Clear the decks before the bank holiday shutdown. Confirm which customers have payment runs scheduled before the year end, and get the answer in writing. Note that Faster Payments and CHAPS cut-off times move over the holidays; an invoice paid on 31 December is not the same as an invoice paid on 2 January.

First week of January. This is the week of leverage. A letter before action issued on 5 January lands in a finance department that has just reopened its ledger. For undisputed sums, a money claim issued online is inexpensive and signals seriousness; it can always be settled.

Mid-January. Make the decision on funding, not on hope. If receipts are not materialising, approach HMRC now rather than on 30 January. Interest on a Time to Pay arrangement continues to accrue, but the penalties and enforcement costs do not.

Final week. File the return. Pay what you have. Keep the arrangement current.

Triage the ledger: where chasing pays

Not every debtor deserves the same effort. Rank the ledger on three questions: how much is owed, how likely payment is, and how quickly it can realistically arrive. A £12,000 debt from a long-standing customer with a functioning accounts department is worth a phone call every three days. A £900 debt from a customer who has already missed two promised dates is worth one letter and a claim, and no further emotional energy.

Be equally clear-eyed about customers whose own finances look strained. Where a buyer is publicly reporting extended payment practices or has filed late accounts, chasing harder in January is sensible; extending further credit to fund their cash flow is not.

When the money genuinely is not there

There are two realistic fallbacks. The first is a Time to Pay arrangement with HMRC, agreed before the deadline. Propose a monthly figure you can sustain through to the summer rather than an optimistic figure that collapses in March, because a missed instalment typically ends the arrangement and reinstates the enforcement route. Be ready to explain your position with a simple cash-flow statement showing debtor days, committed costs and the receipts you expect.

The second is to shorten the gap between work and cash. That may mean offering a modest early-settlement discount to two or three large customers, using invoice finance against a solid ledger, or asking a reliable customer for a stage payment on work in progress. Each has a cost; compare those costs honestly against interest and penalties.

What not to do

Do not use VAT collected on behalf of the Exchequer, or PAYE deducted from staff, as working capital. Both are held on trust in substance and both escalate quickly. Do not put the tax bill on a credit card without calculating the annualised cost. Above all, do not let the deadline pass in silence: a supplier who calls HMRC in the second week of January has options, and a supplier who calls in March has considerably fewer.

The uncomfortable truth is that the tax deadline is the one date in your diary that will not move. Everything else in the cash calendar is negotiable, which is precisely why it should be planned around the fixed point rather than the other way round.