When do I need to do a tax return?

Kirsty Young Advice and Tips, Tax

For new business owners, knowing when you need to do a tax return is a worry. This short blog answers this question from a newly self-employed person’s point of view.

First let’s revisit the basics, as it’s the most common question we get asked.

A reminder about registration

Even with HMRC, things do change! So, the various guidance on when you should notify HMRC after becoming self-employed has altered over the years.

Currently the guidance states that you need to register with HMRC if:

  • You earn over £1000 in a tax year from your business,
  • You need to prove that you are self-employed (for example, to claim tax free childcare)
  • You want to make voluntary (‘Class 2’) National Insurance payments, which you may want to do to qualify for State Pension and other benefits.

As a result, it’s often worth registering soon after you become self-employed, even if you don’t actually have to.

If you are new to self-employment, we suggest that you:

If you need to, you can register with HM Revenue & Customs here. Be aware that it can take time for your Unique Taxpayer Reference (UTR) to be issued by HMRC. You’ll need this to submit your tax return.

You should tell HMRC that you need to file a tax return before the 5th October each year (more on which October below).

So, when is my first return due?

The tax year runs from 6th April to the 5th of April the following year.

Your tax return is then due at the end of January the following year.

For example:

  • The 2023/24 tax year runs from 6th April 2023 – 5th April 2024.
  • Your digital 2023/24 tax return is due by 31st January 2025 at the very latest.
  • Any tax due is also due to be paid then too. So, the latest you can pay tax due is also 31st January.
  • If you meet certain criteria, you may be asked to pay ‘payments on account’ (tax upfront) on account of the current tax year. These payments will therefore increase what is due to be handed over to HMRC in January, with another payment due by 31st July.

The most common reason this occurs is that you have not had enough tax deducted ‘at source’ (if any!) and your tax bill for the year of the return is over £1000.

Moving forward:

  • The 2024/25 tax year runs from 6th April 2024 – 5th April 2025.
  • Your 2024/25 tax return is due by 31st January 2026.
  • Again, any tax due is also due to be paid by 31st January 2026.

Please note that these dates are for online digital tax returns. If you’re still doing them on paper, the deadline is midnight on 31 October 2025.

Timing is important

Make sure you submit your self assessment return on time!

If you submit your self-assessment online later than 31 January, there are consequences.

“You’ll get a penalty if you need to send a tax return and you miss the deadline for submitting it or paying your bill … You’ll be charged interest on late payments.”

And the costs can rack up too. Even if you are just a day late, you’ll have to pay a penalty of £100. Delay by three months and you may have to pay a penalty of £10 a day, for a maximum of 90 days – that’s £900!

What if I started part-way through the year?

If you became self-employed part way through the year, then your tax return deadline follows the tax year you started in.

For example:

  • If you started being self-employed on 1st January 2025, you started during the 2024/2025 tax year.
  • Therefore, your first tax return will be for the year ending 5th April 2025 (the 2024/25 return).
  • This will be due by 31st January 2026.

In this scenario:

  • You end up with a ‘short’ first year of self-employment income (1st January 2025 – 5th April 2025).

In which

  • You will still need to report the full year’s worth of income from other sources, such as a paid job.

Your next year of self-employment income runs in line with the tax year for a full 12 months. In this example, you would need to register with HMRC by 5th October 2025 for a tax return.

NB: There are some instances where HMRC will give you a different one-off deadline, but this is rare.

Give you or your accountant an early Christmas present!

If you want an accountant to complete your tax return for you, be nice to them and make sure they have everything they need to complete a digital tax return on your behalf well before December.

That timescale should ensure they have time to properly check records and calculate exactly how much tax you owe. Then you can pay the correct amount before 31 January.

This also applies to you if you are completing your tax return yourself. We are sure you’d rather be spending time with your family over the festive period than worrying about tax returns!

I’m still confused about tax return deadlines

Your accountant should always be up to date with all the current tax year allowances that you may be able to claim. They should also understand the correct way to deal with expenses, etc, helping you save money on your tax bill.

If you don’t have an accountant, or feel your accountant isn’t being as helpful or as informed as they might be, we’d love a chat about how we can help.