HMRC Self Assessment Deadline Is Today: Register Online Now

Tax Queen

Tax Expert @ Pie

3 min read

What You Must Know

If you earned money outside your main job between 6 April 2025 and 5 April 2026, this deadline may apply to you. If it does, register online today. It only takes a few minutes, and you don't need any figures or accounts ready.

Does This Affect You?

According to Michele Tieghi, founder of Psyfi Money, more than 12 million people are expected to file a Self Assessment tax return, but only around 4.5 million are registered as self-employed.

That leaves roughly 7.5 million people with income from somewhere else: side hustles, day trading, investments or renting out property.

Self Assessment is simply how HMRC collects Income Tax from people whose tax isn't fully taken out of their wages.

If you're employed and your only income comes through payroll, you're probably fine. If you earn money on the side, read on. Pie Tax is a free self assessment app built for exactly this group of people.

The Most Common Reasons You Need to Register

Side Hustle Income Over £1,000

This is the big one. Everyone gets a £1,000 trading allowance each year, which is a tax-free amount for self-employed or side income. Earn more than £1,000 before expenses from selling online, freelancing, tutoring or anything else, and you need to tell HMRC.

Selling Shares Outside an ISA

If you sold shares, funds or crypto outside an ISA (a tax-free savings and investment account), any profit is called a capital gain. You can make up to £3,000 in gains each year tax-free. Go over that and you'll owe Capital Gains Tax, which usually means filing a return.

Dividends Over Your Allowance

Dividends are payments companies make to shareholders. You get a £500 dividend allowance each year. Dividends that fall within your Personal Allowance (the £12,570 you can earn tax-free) aren't taxed either. If you have tax to pay on dividends up to £10,000, you can tell HMRC by 5 October and have it collected through your tax code. Over £10,000, you'll need to register and file a Self Assessment tax return.

Rental and Other Untaxed Income

Rental income from a property, or other income that hasn't had tax taken off, can also mean you need to register. Not sure? Use HMRC's checker on GOV.UK today, not next week.

How to Register Online Today

Registering is quick. You do it online through GOV.UK, answering a few questions about why you need to file.

You're only telling HMRC that you'll be sending a return, so you don't need any income figures, receipts or accounts at this stage.

Before you start, have these ready:

Your Government Gateway user ID, the login you use for HMRC's online services. If you don't have one, you can set one up on GOV.UK.
Your National Insurance number, found on your payslip, P60 or HMRC letters.

Once you're registered, you'll get your Unique Taxpayer Reference (UTR), a 10-digit number you need to file your return.

HMRC's improved online service puts your UTR in your Personal Tax Account within 72 hours, instead of the up to 15 days it takes to arrive by post. Our step-by-step Self Assessment guide covers what comes next.

What Happens If You Miss Today's Deadline?

Missing 5 October doesn't trigger an automatic £100 fine. That fine is for filing your return late, which is a separate deadline (more on that below).

The penalty for registering late is called "failure to notify", which is HMRC's term for not telling it in time that you owe tax. It isn't a fixed amount.

It's based on how much tax is still unpaid after 31 January 2027, so the bigger your unpaid bill, the bigger the penalty. If you register late but pay all your tax by 31 January 2027, you shouldn't get one.

If you register late, HMRC will also give you a new filing deadline of 3 months from the date on its letter. The simplest option is still to register today and skip the worry. This is exactly why Pie Tax was built: to take the guesswork out of deadlines for people who never asked to become tax experts.

The Filing Deadlines to Remember

31 October 2026: Paper Returns

If you file on paper, your return must reach HMRC by 31 October 2026. That's less than a month away, so most people are better off filing online.

31 January 2027: Online Returns and Payment

Online returns and any tax you owe for 2025/26 are both due by 31 January 2027. This is where the automatic £100 penalty applies: miss it and you'll be fined even if you owe nothing.

Leave it longer and the fine grows: £10 a day after 3 months, then extra charges at 6 and 12 months. Those add up to at least £1,600 after a year. Our guide on how to avoid Self Assessment penalties breaks down every stage.

Making Tax Digital: Does It Change Anything?

Since 6 April 2026, sole traders and landlords with qualifying income over £50,000 have had to use Making Tax Digital(MTD) for Income Tax. That means keeping digital records and sending HMRC quarterly updates.

It doesn't change today's deadline. If you need to file for 2025/26, you still register and file through Self Assessment as normal. Pie Tax covers both, and you can see what's free on our pricing page.

How to Make Filing Easier

Once you're registered, don't wait until January. Keep your income and expenses in one place as you go, and you'll have your figures ready long before the deadline.

See how Pie Tax works: it connects to your bank, sorts your transactions and files your return straight to HMRC.

If you earned more than £1,000 on the side, made over £3,000 in gains from shares or had dividends you owe tax on, register with HMRC online today.

It takes a few minutes and you don't need any numbers yet. Registering late could mean a penalty based on your unpaid tax, and filing late means at least £100.

Get started today for free, or download the Pie Tax app and get your 2025/26 return sorted early.

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