How to avoid getting caught out in 2026 as 1.1 million taxpayers miss 2025 Self-Assessment deadline

If you were one of the 1.1 million people who missed the 31 January Self-Assessment deadline, your financial headache is just beginning. 

HM Revenue & Customs (HMRC) has confirmed that those who failed to file on time will face a £100 penalty at a minimum.  

There is an incentive to get this sorted as soon as possible, as the longer your tax return is left incomplete, the higher the fines and interest charges will be. 

It is a reminder that leaving tax returns until the last minute is a costly gamble.  

This year, over 31,000 taxpayers submitted their returns in the eleventh hour, highlighting the unnecessary stress that comes with procrastination. 

The cost of missing the deadline 

So, what exactly happens if you miss the deadline or fail to make your payment on time? 

• £100 fixed fine – Even if you owe no tax, this fine kicks in as soon as the deadline passes. 

• £10 per day – This fine applies if your return is over three months late, reaching up to £900. 

• Five per cent of tax due (or £300) – After six months of delay, you will face a penalty of at least £300 or five per cent of your tax due. 

• Additional five per cent – A second five per cent penalty will apply after twelve months. 

If you do not pay the tax you owe by the deadline, you will face even more charges: 

• Interest – The interest rate is currently 7.25 per cent, but it will rise in April 2025 to a rate four per cent higher than the Bank of England’s base rate. 

• Late payment penalties – After 30 days, you will face an additional five per cent penalty on unpaid tax, with more charges at six months and twelve months. 

This year’s filing fiasco 

The usual Self-Assessment deadline day came with extra stress thanks to IT problems at Barclays.  

Though the bank has assured customers they won’t lose out financially, this serves as a warning: waiting until the last minute can be disastrous.  

Whether it is a bank error or an emergency, submitting your return early is the safest option. 

How to avoid the stress next year 

To avoid the penalties and hassle of late filing, plan ahead: 

• Keep your records organised – Track your finances throughout the year to make your return as easy as possible. 

• Set an earlier deadline – Aim to file your return well before 31 January to leave room for any unexpected delays. 

• Seek expert assistance – A tax professional can help you file your return on time and may even spot opportunities to save you money. 

• Save for your tax bill – Anticipate what you owe and set aside funds in advance. 

If you missed this year’s deadline, don’t wait to take action. The sooner you address it, the better. 

Get ahead for 2026 

Don’t leave it until the last minute. 

Contact us today to get your Self-Assessment in order and ensure you are ready for the next deadline.