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UK Tax

What to do if you missed the UK tax deadline

The stats are in from HMRC and nearly one million people missed the tax return deadline on the 31st January. If you’re one of them then here’s what to do…

Samantha Adams

Wed Feb 12 2020

Firstly, don’t panic! As the figures show, you’re not alone and sometimes a late tax return is better than a rushed and incorrect one (if that applies to you then keep reading too!).

I missed the deadline – what should I do now?

You need to file your tax return and pay your tax bill, both as soon as possible.

1. File a self assessment tax return

The deadline for paper tax returns was 31st October 2019 so you must file your tax return online. To make things less of a scramble, try gather everything you will need to hand, including your unique taxpayer reference (UTR). If it’s your first time filing online you need to register – your UTR and activation code are sent by post so can take up to 10 days.

Do you know all of this but have no idea where to start calculating your cryptocurrency tax? Check out our blog which takes you through it step-by-step.

2. Pay your tax bill

Funnily enough, HMRC have made paying your tax bill very accessible – click here to find out the various ways to pay. If you can’t afford to pay the tax you owe, you may be able to set up a payment plan by logging into your Government Gateway account or by contacting HMRC’s Payment Support Service. We recommend contacting them as soon as possible to avoid further penalties and unnecessary stress.

How much will missing the deadline cost me?

This is dependent on how late you file…

  • File up to 3 months late: you’ll get a fixed penalty of £100
  • More than 3 months late: you’ll be charged £10 a day (up to £900)
  • After six months: HMRC will fine you £300, or charge 5% of the tax you owe, whatever is larger.

You will also face interest on the tax that you owe. You can use the online calculator to estimate how much you may need to pay.

Can I appeal?

Anyone with a legitimate excuse for missing the tax deadline can talk to HMRC to avoid fines. Those with genuine excuses will be treated leniently as HMRC try to focus penalties on repeat offenders and tax evaders, however they may ask you to provide evidence to prove your case.

What’s a valid excuse?

HMRC showed they can have a sense of humour when they shared some of the weirdest excuses they’ve received…


Funnily enough these were not accepted! Below are some of the reasonable excuses HMRC may accept; normally unexpected events that fall out of your control and occur close to the deadline.

Legitimate excuses for appealing a penalty:

  • A serious or life-threatening illness
  • An unexpected hospital stay
  • The death of a partner or close family member
  • Fire, flood or theft
  • Computer or software failure
  • Issues with HMRC’s online services

How do I appeal?

You can appeal online but only after you have filed your tax return (or informed HMRC that you didn’t need to file).

You’ll need:

  • the date the penalty was issued
  • the date you filed your Self Assessment tax return
  • details of your reasonable excuse for late filing

You can appeal online through a Government Gateway account or by post using form SA370 (or a letter). Each appeal is dealt with on a case by case basis.

I submitted my tax return on time but made an error - what can I do?

You can resubmit your tax return before the next deadline but you must inform HMRC of the change. You may be penalised if found to have submitted incorrect information whether it was done deliberately or through accidental carelessness.

How can I be more prepared for next years deadline?

Keep an eye out for our next blog if you want to avoid the stress, hassle and cost of late filing in future. In this we’ll be discussing techniques for how to stay on top of crypto tax throughout the year, eg. with Recap 😉, and how to turn the mammoth admin task into just a few clicks of a button when tax season approaches.