Your Self Assessment year at a glance

When you're working for yourself, there's already plenty to keep on top of. Between managing your customers, doing the work and keeping your business running, it's easy for tax deadlines to slip down the list.

The good thing is that Self Assessment follows a fairly predictable timetable. Once you understand which dates matter and what happens on each one, it's much easier to plan ahead.

We've put together this straightforward guide to help you know what's coming and avoid any unexpected surprises.

There are a few other useful dates too, so let's go through them.

Your Self Assessment calendar

These are the main dates that come around every year.

Date	What happens	What it means for you
6 April	The new tax year begins.	A fresh tax year starts. It's a good time to get your records organised.
31 July	The second payment on account is due.	If you make advance payments towards your tax bill, this is when the second instalment is due.
5 October	The deadline to register for Self Assessment for the previous tax year.	If you've started working for yourself and need to submit a return, this is an important date.
31 October	The deadline for paper tax returns.	Only relevant if you're submitting a paper return rather than filing online.
30 December	The early online filing deadline for eligible taxpayers who want HMRC to collect their bill through their tax code.	This may apply if you also have a job or pension and owe less than £3,000.
31 January	The online tax return and main payment deadline.	Your return must be submitted and any outstanding tax paid. Your first payment on account may also be due.
5 April	The tax year ends.	Time to make sure your records for the year are complete and ready for your next return.

Not every date will apply to everyone. For most self-employed people filing online, 31 January is the main deadline to remember.

Your deadlines for the 2025/26 tax year

If you're completing a tax return for income earned between 6 April 2025 and 5 April 2026, these are the dates you need.

Date	What's due
5 October 2026	Deadline to register for Self Assessment, if required. This date has now passed.
31 October 2026	Paper tax return deadline.
30 December 2026	Online filing deadline if you want to pay an eligible tax bill through your PAYE tax code.
31 January 2027	Online tax return deadline, payment of any outstanding tax for 2025/26 and your first payment on account for 2026/27, if applicable.
31 July 2027	Second payment on account for 2026/27, if applicable.

Missed the 5 October registration deadline?

Don't ignore it. If you needed to register and haven't done so, tell HMRC as soon as possible.

HMRC may give you a later deadline to submit your return if you register late, but any tax you owe will still normally need to be paid by 31 January 2027.

Do I need to register for Self Assessment?

If you're self-employed and your total trading income was more than £1,000 during the 2025/26 tax year, you will generally need to register for Self Assessment.

That's £1,000 before expenses, not the profit you've made after paying your business costs.

For example, if you earned £1,500 from your business but spent £700 on supplies, your trading income before expenses would still be £1,500.

There are also circumstances where you may need to register even if your income is below £1,000, so it's worth checking if you're unsure.

If you're already registered and regularly submitting Self Assessment returns, you generally won't need to register again. However, if you were previously registered for a different reason or stopped submitting returns, you may need to update or reactivate your registration.

A change coming in April 2027

Following the October 2026 Budget, the government has announced that the trading allowance and Self Assessment trading income reporting threshold will increase from £1,000 to £3,000 from 6 April 2027, subject to legislation.

This means the rules are changing for future tax years, but the increase does not apply to your 2025/26 return or the 2026/27 tax year.

For now, the £1,000 threshold remains relevant when checking whether you need to register for those years.

What's a payment on account?

This is one of the parts of Self Assessment that can catch people out, especially when they're submitting their first tax return.

A payment on account is an advance payment towards your next tax bill.

Instead of waiting until the following January to pay everything, HMRC may ask you to pay some of your tax in advance, split into two instalments.

The payments are due on:

• 31 January
• 31 July

Each payment is normally half of the previous year's relevant tax bill.

You'll generally need to make payments on account unless your previous year's relevant tax liability was less than £1,000, or more than 80% of the tax you owed was already collected outside Self Assessment, such as through your wages.

Your HMRC account will show whether you need to make them and how much is due.

Why your first January tax bill can be bigger than expected

Imagine you've just completed your first Self Assessment tax return, and your Income Tax and Class 4 National Insurance bill is £4,000.

You might reasonably expect to pay £4,000 in January.

However, if you're required to make payments on account, HMRC will also ask you to pay the first instalment towards the next tax year.

So your January payment would look like this:

What you're paying	Amount
Tax for the year you've just finished	£4,000
First payment on account towards the next year	£2,000
Total due on 31 January	£6,000

Then, on 31 July, you'd pay your second payment on account of £2,000.

That means you've paid £8,000 across January and July, although £4,000 of it is being paid towards the following tax year.

It's important to understand that you aren't being charged twice for the same income. You're paying the tax you owe for one year while making advance payments towards the next.

Once you're making regular payments on account, some of your tax is already being paid throughout the year.

However, if your actual tax bill is higher than the advance payments you've made, you may still have a balancing payment to make the following January.

Our tip: Start setting money aside for tax as soon as your customers pay you. That way, you're building up a pot for your future tax payments rather than trying to find the money when the deadline arrives.

What if my income has dropped?

Not every year in business looks the same.

Perhaps you've reduced your working hours, lost a customer or simply had a quieter year than expected.

If you think your next tax bill will be lower than the previous year's, you can ask HMRC to reduce your payments on account.

This can make a real difference to your cash flow, particularly if you're already feeling the effects of a quieter period.

Just be careful not to reduce them too far. If your final tax bill turns out to be higher than your reduced payments, HMRC will charge interest on the difference.

If you're unsure how much to reduce them by, it's worth getting some advice first.

Can I submit my tax return before January?

Absolutely! In fact, we'd encourage it.

You can submit your tax return as soon as the tax year has ended, provided you have all the information you need.

For the 2025/26 tax year, that means you could have submitted your return from 6 April 2026.

You don't have to pay your tax bill immediately just because you've filed your return early.

The normal payment deadline is still 31 January 2027.

Filing earlier simply gives you more time to understand what you owe, budget for the payment and avoid the last-minute January rush.

It's also an opportunity to identify any missing information or questions before the deadline is approaching.

Can I pay my tax through my wages?

In some circumstances, yes.

If you're self-employed alongside having an employed job, or you receive a pension that's taxed through PAYE, HMRC may be able to collect your Self Assessment bill through your tax code.

This means the tax is deducted gradually from your wages or pension rather than being paid as one lump sum.

To qualify, you must generally:

• Owe less than £3,000 on your Self Assessment bill.
• Already pay tax through PAYE.
• Submit your online tax return by 30 December.
• Meet HMRC's other eligibility requirements, including having enough PAYE income to collect the amount owed.

This isn't available to everyone, but it's useful to know about if you have both employed and self-employed income.

What happens if I miss a deadline?

Missing a Self Assessment deadline can be expensive, even if you don't actually owe any tax.

If you're required to submit a return and miss the filing deadline, HMRC will normally issue an initial £100 penalty.

Leave it longer, and additional penalties can apply.

If you don't pay your tax bill on time, HMRC can also charge interest and late payment penalties.

The important thing is not to ignore the situation.

If you've missed a deadline, take action as soon as possible. If you can't afford to pay your bill in full, speak to HMRC about your options. You may be able to arrange a payment plan.

And if you're not sure what to do next, we're here to help.

A little preparation goes a long way

Self Assessment doesn't need to be something you dread every January.

Keeping your business records organised, putting money aside regularly and knowing your deadlines can make the whole process much more manageable.

You don't need to become a tax expert. You just need to understand what applies to you and have the right support when you need it.

This guide covers the main UK Self Assessment deadlines and rules as at October 2026. Individual circumstances can affect whether you need to register, submit a return or make payments on account.