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Last-minute online tax return tips

Self-assessment tax return deadline is midnight January 31

More than 10 million people have to submit a self-assessment tax return to HMRC

The deadline to submit your self-assessment tax return to HMRC is January 31. Here, we offer some top tips for those who have yet to submit their return.

Four steps to submitting your tax return on time

1. Use the Which? tax calculator

The Which? tax calculator is an easy-to-use jargon-free tool which offers personalised tax tips and even submits your return directly to HMRC for you.

It also comes with extensive help notes, which ensure you claim for full allowances and tax reliefs.

2. Don’t leave it until the last minute

You can submit your tax return at any time up until midnight on 31 January to avoid a fine – but don’t leave it until the last minute.

HMRC has introduced a two-step verification process for people using self-assessment, so you may need to provide a P60, mobile number or another form of identity to log in.

This should only add a few seconds to the log-in process for most people, but if you don’t have the documents requested, you’ll have to call HMRC to verify your identity.

3. Estimate figures you don’t have

Don’t miss the deadline because you’re missing the exact figures needed for your tax return.

Online returns allow you to enter an estimate figure where necessary, so do this and submit your return on time.  

You’ll need to amend your return with the actual figure as soon as you have it.

4. Look for acknowledgement from HMRC

Once you submit your online return, an acknowledgement should appear on the screen with a submission receipt reference number. 

You should also receive an email acknowledgement from HMRC. Use these as proof you met the 31 January deadline.

What to do if you miss the January 31 deadline

Those who fail to submit their online tax return by midnight on January 31 will receive an automatic £100 fine, but you should still aim to submit as quickly as possible afterwards.

If you continue to delay, your fine will increase. After three months, you’ll start to be fined £10 a day. After six months, you’ll face another £300, or 5% of the tax owed (whichever is higher) on top of these penalties. Further fines may follow, so you’re better off submitting your return as soon as you can.

There are certain circumstances in which HMRC will waive fines for late submissions. These are covered in detail in our consumer rights tax guide

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