Self-assessment checklist

Here are the dates to remember for filing a self-assessment tax return online:

January 31: Deadline for filing self-assessment return online

You have until midnight on this date to submit your return using HMRC’s online service.

January 31: Deadline for paying tax due for previous financial year

Whether you file your return online or by post, your tax bill has to be settled by midnight on January 31.

January 31: First payment on account for current financial year

April 5: Financial year ends

The financial year runs from April 6 to April 5 the following year.

July 31: Second payment on account for financial year just ended

This is when the other half of the expected tax bill for the most recent financial year is due.

If you expect to pay less tax for this period – for example if your income has fallen, or you have made no capital gains – tell your tax office and your payment on account can be reduced.

October 5: Deadline for registering for self-assessment

If you are not already registered for self-assessment and your tax office does not know you need to file a return for the previous financial year, you should inform HM Revenue & Customs before this date. Click here to register.

If you don’t register by October 5 and you fail to pay any tax owing in time, you could face extra penalties.

October 31: Deadline for filing paper self-assessment forms

If you are filing your return by post, the form needs to have arrived at your tax office by midnight on this date.

Your tax office will also charge you half of the tax it expects you to pay for the current financial year. Unless you tell officials otherwise, this is usually half of your previous year’s bill.

Read our guide to self-assessment scams. 

What are the penalties for late filing of your self-assessment online? 

If you file your return late, you will be charged £100. This penalty used to be applied only in cases where tax was owed, but now you can be fined whether you owe tax or not.

If your return is three months late, you could then face £10-a-day fines for the subsequent 90 days.

After six months a further £300 can be charged, or 5% of any tax owed if that figure is greater.

What are the penalties for late payment?

HMRC charges interest on any late payments and also imposes one-off fines of 5% of the tax owed if it is still unpaid by the end of February.

Further 5% fines can be levied after six and then 12 months.

A guide to completing a tax self-assessment form online...