The deadline for Self-Assessment taxpayers to submit their online tax return is just two months away and many self-employed individuals, sole traders and landlords will be organising their accounts.

With 31 January 2026 fast approaching, there is very little time left to organise your accounts and submit your return to HM Revenue and Customs (HMRC), but you will need to do it if you want to avoid potential fines and sanctions.

Why leaving your submissions late is challenging

The longer you leave your legal obligations, the more pressurised it can be to gather all the information you need, speak with the right people and collate everything correctly.

You will have missed your chance to budget, as you could have submitted your returns early and paid the tax owed at a later date ahead of the deadline.

Instead, you’re in a position where both actions will need to be done at the same time and you need to be sure the figures you have calculated are accurate.

As the deadline approaches, the pressure rises significantly, increasing the likelihood of errors in your submission, which HMRC do not take kindly to.

There is also the introduction of Making Tax Digital (MTD) for Income Tax to consider, as this will completely change how some Self-Assessment taxpayers keep a record of their accounts and submit reports to HMRC.

Self-Assessment Taxpayers who meet the MTD requirements will need to keep digital records of their accounts and submit quarterly reports to HMRC from April 2026.

Individuals whose income meets or exceeds £50,000 will need to abide by these laws in the new year. The threshold then decreases to £30,000 from 2027 and £20,000 from 2028.

With the current submission deadline not far away, it’s essential you start the process of filing your return now to take away any added pressure and last-minute scramble when the New Year comes around.

What are the dangers of missing your deadlines and underpaying your taxes?

Ahead of the submission deadline, it’s important you organise your accounts and gather all the information you need, like your Unique Taxpayer Reference (UTR) number.

Organising your accounts gives you visibility on all the important aspects, including your income, outgoings, business costs and expenses, current tax obligations and your overall turnover.

It is essential that you calculate everything correctly because underpaying your taxes has serious consequences.

There is a risk of fines and potential investigations into your finances, figures and submission returns in detail from HMRC, looking for any further irregularities or suspicious activity.

For sole traders and landlords, any HMRC investigations can be impactful for your reputation and lead to loss of custom and interest in your services, which will impact your revenue and profit.

Missing your deadlines by even a day can result in an automatic fine of £100, with additional charges to follow if you continue to slack on your responsibilities.

The fines will become more severe the longer you ignore your deadlines and communications from HMRC.

After 30 days of a payment being late, an initial fine is given out, which will be five per cent of the tax owed.

Should you continue to ignore the penalty after six months, an additional five per cent penalty of the tax due is added on top.

In total, you could face a fine totalling 15 per cent of your tax bill, as an additional five per cent of that bill is added to the fine 12 months after the initial payment was due.

There is even the potential for legal action and criminal investigations which can bring prison sentences if you persistently miss your deadlines.

How our team of accountants can help you

As you need to act now, it’s important to access the necessary support if you need it and our team of accountants is here for you.

We can help you organise everything ahead of time, help you work out your figures to determine the tax you owe and ensure you can build a clear picture of your finances.

We give you the tools to confidently meet your legal obligations. With the deadline fast approaching, there has never been a better time to plan ahead and take away any last-minute stress or panic.

For support in submitting your Self-Assessment tax return, contact our team today.