“I’ve got until 31 January.”

Technically? Yes.

Strategically? Barrons would suggest a slightly different approach.

For most people completing an online Self Assessment tax return for 2025/26, 31 January 2027 is the filing and payment deadline.

But a deadline tells you when something must be finished. It doesn’t tell you when you should start.

You can complete your tax return now

One of the biggest misconceptions surrounding Self Assessment is that tax returns are a January job.

They’re not.

Tax returns for the year ended 5 April 2026 can be submitted any time from 6 April 2026 up to the relevant filing deadline.

That means there’s no need to wait for January.

1. You’ll know your tax bill earlier

Perhaps the biggest advantage of completing your tax return early is certainty.

Once your return has been prepared, you’ll have a much clearer picture of what you owe.

Instead of discovering your tax liability shortly before it needs paying, you could potentially know the figure months beforehand.

2. Filing early doesn’t mean paying early

This is an important distinction.

Completing and submitting your tax return ahead of time doesn’t generally bring forward the normal 31 January payment deadline.

You can therefore get the return off your to-do list while retaining the time available to plan for the payment.

3. It makes cash-flow planning easier

Nobody particularly enjoys an unexpected tax bill.

For business owners, landlords and self-employed individuals in particular, knowing what’s due early can make cash-flow management considerably easier.

It gives you time to make sure sufficient funds are available rather than having to find them at short notice.

4. There’s time to deal with missing information

Missing dividend statement?

Can’t find an old bank statement?

Waiting for information about an investment?

These situations are considerably easier to deal with in September than at the end of January.

Providing your information to Barrons early gives us time to identify anything that’s missing and work with you to resolve it.

5. You reduce the risk of penalties

Miss the filing deadline and an initial £100 penalty can apply, even if there is little or no tax to pay.

Further penalties can follow the longer a return remains outstanding, while late payment can result in interest and additional penalties.

Leaving your return until the final days creates a risk that simply doesn’t need to be there.

6. January is busy enough

New year. Back to work. New business plans. Christmas credit card statements.

Do you really want “find all my tax paperwork” on that list too?

Getting your Self Assessment dealt with early means January can be spent focusing on the year ahead rather than looking backwards at the last one.

So, when should I send my information to Barrons?

As soon as you have everything available.

You don’t receive a prize for submitting your tax return on 31 January at 11:58pm.

But you do get something considerably more useful from completing it early: certainty.

If you’re an existing Barrons client, send your information to your usual contact and we’ll get the process moving.

If you’re looking for an accountant to help with your Self Assessment, our Personal Tax team can help you understand your obligations, prepare your return and make sure you know what you need to pay and when.

This article is general information and does not constitute individual tax advice.