# Missed the Self Assessment deadline? Penalties and what to do next > What normally happens when a UK Self Assessment return is late, how HMRC penalties build up from £100 to over £1,600, and the practical steps to take now. Canonical: https://yestax.co.uk/tax-help/missed-self-assessment-deadline-penalties Last updated: 2026-09-10 Published: 2026-09-03 Author: YesTax Editorial Team Reviewed by: Qualified UK Tax Accountant (CTA / ATT) > **Key Takeaways for Late Tax Returns:** > - **Immediate £100 Fine:** Applies 1 day after the 31 January deadline, even if no tax is owed. > - **Penalty Escalation:** After 3 months, fines increase by **£10 per day** (up to £900 extra). At 6 and 12 months, additional 5% or £300 charges apply. > - **Separate Late Payment Penalties:** If tax is unpaid at 30 days, 6 months, and 12 months, 5% surcharges are added each time plus statutory interest. > - **File Now to Stop Daily Escalation:** Submitting your return immediately caps further penalty accumulation. If your Self Assessment return is already late, **file it as soon as you can rather than waiting for the tax problem to become tidy**. Late filing and late payment are separate issues, so leaving the return outstanding can make the position worse even if you cannot yet pay the bill in full. ## The standard late-filing penalties For Self Assessment returns under the standard late-filing regime, HMRC currently sets out the following escalation: - an initial **£100** late-filing penalty; - after 3 months, **£10 per day** for up to 90 days, so up to another £900; - after 6 months, a further penalty of **5% of the tax due or £300, whichever is greater**; - after 12 months, another **5% of the tax due or £300, whichever is greater**. The initial filing penalty is not simply cancelled because no tax happens to be due. Late payment has its own consequences. HMRC says late-payment penalties can arise at 30 days, 6 months and 12 months, and interest is also charged on overdue tax. ## File first, then deal with payment A common mistake is to think there is little point filing until you can pay. That combines two problems unnecessarily. Filing the return can: 1. stop further filing delay; 2. establish the actual amount due rather than relying on estimates; 3. make it easier to discuss payment with HMRC; 4. expose any errors or missing years that need separate attention. If records are incomplete, work out what can be reconstructed from bank statements, payslips, property records, accounting software, brokers, platforms or third parties. Do not invent numbers merely to submit something quickly. ## If several tax years are outstanding When more than one return is late, treat each tax year separately. Gather: - which returns HMRC expects; - the filing deadline for each return; - which returns have already been issued or requested by HMRC; - tax and payments on account already paid; - any determinations, penalties or collection letters received; - the income sources relevant to each year. Several years of missing returns can create a much larger-looking HMRC balance because estimated liabilities, penalties and interest may sit alongside the actual tax position. ## What if you have a reasonable excuse? You may be able to appeal a penalty if something genuinely prevented you meeting the obligation. HMRC gives examples such as serious illness, an unexpected hospital stay, bereavement close to the deadline, certain service failures, fire, flood or other circumstances that made compliance impracticable. The facts matter. A reasonable excuse is not a magic phrase to attach to every late return. You should normally put the position right as soon as the excuse ends. Keep evidence of the event and the dates involved. ## A note about Making Tax Digital penalties Do not assume every Income Tax submission now follows exactly the same penalty rules. A points-based late-submission regime is being introduced for Income Tax Self Assessment customers as they become mandated into Making Tax Digital for Income Tax from the 2026 to 2027 tax year onward. That can affect regular MTD submission obligations. If you are dealing with an **annual Self Assessment return**, an **MTD quarterly obligation**, or both, identify exactly which submission is late before calculating penalties. ## What to gather before asking for help A useful first pack is surprisingly small: 1. your UTR if you have it; 2. the tax years that are outstanding; 3. copies of any HMRC penalty or collection notices; 4. a list of the income sources for each year; 5. the records you currently have and what is missing; 6. any reason the return could not be filed on time, with dates. If the return is late **and** you cannot pay the expected tax, mention both facts. The solution may involve completing the return and dealing with the debt as two coordinated steps rather than one vague emergency. ## Common questions ### Is the first late Self Assessment filing penalty still £100 if no tax is due? Yes. Under the standard Self Assessment late-filing regime, HMRC applies an automatic fixed penalty of £100 even if you have zero tax to pay or are owed a refund. ### Should I wait until I can pay before filing a late return? No. Filing and payment are separate obligations. Delaying filing causes daily penalties to accumulate (£10/day after 3 months up to £900), regardless of whether you have the money to pay. ### Can I appeal a late-filing penalty? You can appeal if you have a genuine 'Reasonable Excuse' (such as unexpected hospitalization, serious illness, or bereavement). HMRC requires appeals within 30 days of the penalty notice. ## Primary sources - [GOV.UK: Self Assessment tax returns — penalties](https://www.gov.uk/self-assessment-tax-returns/penalties) - [GOV.UK: Self Assessment tax returns — deadlines](https://www.gov.uk/self-assessment-tax-returns/deadlines) - [GOV.UK: Disagree with a tax decision or penalty](https://www.gov.uk/tax-appeals/penalty) --- This page is general information, not individual tax, legal or financial advice.