Right about now, a particular envelope tends to land on the doormats of Britain's self-employed: the reminder that a payment on account is due by 31 July. If you're a sole trader, a landlord, or anyone who files a Self Assessment return, you've probably had the nudge from HMRC already. And if the number on it made your stomach drop a little, you are very much not alone.
The summer payment on account is one of the most misunderstood dates in the whole tax calendar. It isn't a new bill, it isn't a penalty, and it isn't optional in the way some people assume. It's a prepayment towards a tax year that hasn't even finished yet, and that is precisely why it catches people out. You can owe several thousand pounds in July for income you won't fully earn until the following April. Understanding how it works — and what your options are if the cash simply isn't there — is the difference between a manageable summer and a nasty autumn.
What the 31 July payment on account actually is
Payments on account are HMRC's way of collecting your Income Tax in advance, in two instalments, rather than in one lump after the year ends. The system kicks in once your Self Assessment bill goes above £1,000 and less than 80% of your tax is already collected at source (through PAYE, for instance). When that happens, HMRC assumes next year's bill will look much like last year's, and asks you to pay it in two halves.
The first instalment is due by 31 January, alongside any balancing payment for the previous year. The second is due by 31 July. Each instalment is, by default, 50% of your previous year's tax bill. So if your 2024/25 liability came to £6,000, you'd have paid £3,000 in January 2026 and you'll owe another £3,000 this coming 31 July — a payment towards the 2025/26 year that only ended in April. Class 4 National Insurance gets bundled into these instalments too, but Class 2 and Capital Gains Tax do not.
Here's the part that trips people up most often. Because the July payment is based on last year's income, it takes no account of whether this year has been better or worse. A freelancer who had a storming 2024/25 and a quiet 2025/26 still gets asked for a payment sized to the good year. That mismatch is the single biggest reason the July deadline causes panic.
The reduce-your-payment trap
If your income really has fallen, you can apply to reduce your payments on account. You do this through your HMRC online account or on form SA303, and it's a genuinely useful lever — there's no reason to lend HMRC money it will only refund you later.
But be careful here, because this is where people get burned. If you reduce your payments and it turns out you've under-claimed — your income held up better than you guessed — HMRC charges interest on the shortfall, backdated to the original due dates. As of mid-2026 that late-payment interest sits at 8.75% (the Bank of England base rate plus 4 percentage points), which is not a trivial cost. Reducing your payment because you're optimistic is a gamble; reducing it because your turnover genuinely collapsed is sensible. Know which one you're doing.
My straightforward advice: only reduce if you have real evidence the year has been leaner — fewer invoices, a lost contract, a tenant void, a stretch of illness. If you're simply hoping things pick up, leave the figure alone and overpay slightly rather than risk the interest.
What happens if you genuinely can't pay
This is the question nobody likes to ask out loud, so let's deal with it plainly. If the money isn't there by 31 July, the worst thing you can do is ignore the deadline and hope. Interest starts accruing the day after, and silence is what turns a cashflow wobble into an enforcement problem.
The right move is to set up a Time to Pay arrangement. This is HMRC's instalment plan for people who can't clear a tax bill in one go, and it's far more accessible than most sole traders realise. If you owe less than £30,000, you're within 60 days of the payment deadline, and your tax returns are up to date, you can usually set it up yourself online without ever speaking to anyone — the self-serve route lives in your Government Gateway account. Larger amounts or messier situations mean a phone call to the Self Assessment payment helpline, where they'll ask about your income and outgoings and agree a monthly figure you can actually manage.
A Time to Pay arrangement doesn't make the interest disappear — it still runs at the 8.75% rate on the outstanding balance until you've cleared it. What it does do is stop the situation escalating: no late-payment penalties pile up while you're keeping to the plan, and HMRC won't pass you to debt enforcement. Crucially, you have to keep filing and paying everything else on time. Miss a monthly instalment or fall behind on a future return, and the arrangement can be cancelled, putting the whole balance back on the table at once.
Making Tax Digital is about to change the rhythm
If you're a sole trader or landlord, there's a structural change bearing down that will reshape how all of this feels. Making Tax Digital for Income Tax begins phasing in from April 2026 for those with qualifying income above £50,000, dropping to the £30,000 threshold in April 2027. Once you're in it, you'll keep digital records and send HMRC quarterly updates through compatible software, replacing the single annual return habit.
It's worth being clear about one thing, because the rumour mill gets this wrong: those quarterly updates are not four tax bills. Payments on account remain twice a year, on 31 January and 31 July, exactly as now. What changes is the visibility — you'll have a running, software-driven picture of your figures through the year rather than a once-a-year reckoning. The optimistic read is that fewer people will be blindsided by a July payment they didn't see coming. The catch is the admin overhead of four submissions plus a final declaration, which for a one-person business is real work nobody's reimbursing you for.
How to make next summer hurt less
The cleanest fix for the July squeeze is boring and it works: open a separate savings account the day you start trading, and move a fixed slice of every payment you receive into it. For most basic-rate sole traders, putting aside 20% covers Income Tax and Class 4 National Insurance with a little headroom; if you're nudging into higher-rate territory, 30% is closer to the mark. Treat that account as untouchable — it isn't your money, it's HMRC's, you're just holding it.
A few habits that take the sting out of the deadline:
- Check your personal allowance position. For 2026/27 the standard Personal Allowance is £12,570, frozen yet again, and it tapers away entirely once your income passes £125,140 — a quiet squeeze that pushes more people into higher tax than they expect.
- File your return early, not in January. Knowing your number in May or June gives you months to plan the July payment, instead of discovering it days before it's due.
- If your year genuinely dipped, submit the reduction claim properly rather than just paying late — late payment costs you interest, a valid reduction doesn't.
- Set a calendar reminder for mid-July, not the 31st. Bank transfers and Faster Payments to HMRC are quick, but a card payment that bounces or a missed reference can cost you days you don't have.
The taxpayers who sail through 31 July aren't the ones earning the most. They're the ones who treated the payment as a known quantity months in advance and quietly set the cash aside. The bill was always coming. The only real choice you have is whether it arrives as a shock or as a line item you'd already budgeted for.