Self Assessment Deadlines Guide
Key HMRC Self Assessment dates for registering, filing and paying, plus an instant estimate of what a late filing or late payment could cost you.
Estimate Your Late Filing & Payment Penalties
Enter how many days late your return or payment is, along with any tax owed, to instantly see an estimate of HMRC’s penalties and interest.
Penalty Estimator
Based on standard HMRC Self Assessment penalty rules.
How it Works
Understanding the penalty estimate
Fixed £100 Penalty
An automatic £100 penalty applies the moment your return is even one day late, regardless of whether you owe any tax.
Daily & Milestone Penalties
Further penalties are added at 3, 6 and 12 months late, including a £10 daily charge and additional fixed or percentage-based charges.
Late Payment Penalties
Separately, unpaid tax attracts a 5% penalty at 30 days, 6 months and 12 months late, calculated on the outstanding balance each time.
Daily Interest
HMRC also charges daily interest on unpaid tax from the payment deadline until it is settled, using the rate you entered above.
Key Self Assessment Deadlines
A general overview of the main HMRC Self Assessment dates you need to know for each tax year.
| Deadline | Date | What It’s For |
|---|---|---|
| Register for Self Assessment | 5 October | New sole traders, landlords, or first-time filers |
| Paper Tax Return Deadline | 31 October | Filing a return on paper rather than online |
| Online Tax Return Deadline | 31 January | Filing your return via HMRC’s online service |
| Balancing Payment Deadline | 31 January | Paying any tax owed for the previous tax year |
| First Payment on Account | 31 January | Advance payment toward the current tax year |
| Second Payment on Account | 31 July | Second advance payment toward the current tax year |
Self Assessment FAQ
Answers to the most frequently asked questions about Self Assessment deadlines and penalties.
The deadline to file your Self Assessment tax return online is 31 January following the end of the tax year, which is the same date your tax bill must be paid. Paper returns must be filed earlier, by 31 October, and you must register for Self Assessment by 5 October if you are new to it.
Missing the filing deadline triggers an automatic £100 penalty even if you have no tax to pay, with further daily penalties after three months and additional charges after six and twelve months. Missing the payment deadline separately triggers late payment penalties and daily interest on the outstanding tax.
Yes. HMRC allows appeals against penalties if you have a reasonable excuse, such as a serious illness, bereavement, or a technical failure with HMRC’s own systems. You generally need to appeal within 30 days of the penalty notice and explain why the return or payment was late.
HMRC offers Time to Pay arrangements that let you spread your tax bill into instalments if you cannot pay in full by the deadline. It is usually far better to contact HMRC and set this up before the deadline than to simply miss the payment, as this can reduce the penalties applied.