Tax & compliance
What happens if I file my tax return late?
By Pick My Accountant Editorial · Updated 9 July 2026
The penalty ladder in practice
A return that's a year late with £5,000 owed racks up roughly: £100 fixed + £900 daily penalties + two further penalties of at least £300 each — over £1,600 in filing penalties alone, before the three separate 5% late-payment surcharges (£750) and interest. The system is deliberately front-loaded so the cheapest moment to act is always now: each threshold you cross adds a new, unavoidable layer.
If you can't pay, still file
Filing and paying are penalised separately — so filing on time with an unpaid bill avoids the entire filing ladder. Then call HMRC (or apply online) for a Time to Pay arrangement, typically spreading the bill over months; a plan set up before the payment surcharge dates prevents the 5% hits, though interest still runs. The worst strategy is silence: penalties compound and HMRC can eventually estimate your tax for you at an unflattering figure.
Appeals and reasonable excuse
You can appeal any penalty within 30 days if you have a reasonable excuse — serious illness, bereavement close to the deadline, fire or flood, or HMRC's own system failures. Pressure of work, a slow accountant, or not knowing the rules don't qualify. If the excuse is genuine, appeal in writing with evidence; accountants routinely get fair penalties overturned, and even unfair daily penalties reduced.
An accountant as deadline insurance
One £100 penalty is more than two months of a typical sole trader package — and a 12-month spiral costs a year of fees. If you've already missed a deadline, a firm can file quickly, negotiate Time to Pay, and handle the appeal; if you haven't, the calendar ownership alone justifies the retainer for most busy owners. Try our penalty calculator to see your current exposure, then compare firms.
People also ask
Do penalties apply if I'm owed a refund?
Yes — the £100 fixed penalty and daily penalties apply even when no tax is due, which feels outrageous and is nonetheless the law. The tax-geared 6- and 12-month penalties have a £300 minimum for the same reason.
What about a late corporation tax return?
Companies face a separate ladder: £100 late, another £100 at three months, then 10% of unpaid tax at six and twelve months — and repeated lateness doubles the fixed penalties. Companies House charges its own penalties for late accounts on top.
Will HMRC really charge interest on top of penalties?
Yes — late payment interest runs daily on unpaid tax and on unpaid penalties, at a rate linked to the Bank of England base rate. It's not negotiable, which is why Time to Pay early is worth arranging.
This article is general information for UK businesses, not tax, legal, or financial advice, and thresholds change — confirm current rules on GOV.UK or with a qualified accountant before acting. Fee figures are indicative benchmarks from ourmethodology.