What is a payment on account in self-assessment?

Payments on account are advance payments toward your next year's tax bill. If your last self-assessment bill was over £1,000, you make two equal payments: one on 31 January (with your return) and one on 31 July. Each is 50% of the prior year's tax bill. Any remaining balance is settled on the following 31 January.

What is the SA100 form?

The SA100 is the main self-assessment tax return form. Additional supplementary pages include SA101 (additional income), SA102 (employment), SA103 (self-employment), SA105 (UK property), SA106 (foreign income), SA108 (capital gains), and SA109 (non-residence). Most people file online using HMRC's service rather than paper forms.

Can I reduce my payments on account?

Yes. If you expect your income in the next tax year to be lower, you can apply to reduce your payments on account using form SA303 via your HMRC online account or by phone. However, if you reduce them too much and underpay, HMRC will charge interest on the difference from the original due date.

Self Assessment Deadlines UK 2025-26

Q: Who needs to complete a self-assessment tax return?

You need to complete self-assessment if you: are self-employed and earned more than £1,000; are a company director; earned over £100,000; have untaxed income over £2,500; are a high earner receiving Child Benefit (if you or partner earns over £60,000); receive income from abroad; or have capital gains above the annual exempt amount.

Q: When is the self-assessment registration deadline?

You must register for self-assessment by 5 October following the end of the tax year in which you first needed to file. For the 2024-25 tax year (ended 5 April 2025), the registration deadline is 5 October 2025. For 2025-26, it is 5 October 2026.

Q: What is Making Tax Digital for income tax?

Making Tax Digital (MTD) for Income Tax Self-Assessment requires self-employed people and landlords with income over £50,000 to keep digital records and submit quarterly updates to HMRC from April 2026. Those with income between £30,000 and £50,000 must comply from April 2027.

Do I Need to Complete Self-Assessment?

Tick all that apply to you in the 2024-25 tax year (6 April 2024 – 5 April 2025):

I was self-employed with income over £1,000

I am a company director

My total income exceeded £100,000

I received Child Benefit and I or my partner earned over £60,000

I had untaxed income over £2,500 (e.g. savings, dividends)

I received income from renting out property

I had capital gains above the annual exempt amount (£3,000)

I received foreign income

HMRC sent me a notice to complete a return

The 5 Self-Assessment Deadlines You Must Know

Self-assessment involves up to five separate deadlines, each with its own penalties for missing it. Here they are in chronological order for the 2024-25 tax year:

5 October 2025

Register for Self-Assessment

If you have not previously been registered for self-assessment but needed to be for 2024-25 (e.g. first year self-employed, first year receiving rental income), you must register by 5 October 2025. Register online at gov.uk/register-for-self-assessment or by calling HMRC on 0300 200 3310.

31 October 2025

Paper Tax Return Deadline

If you prefer to file a paper SA100 return rather than online, it must reach HMRC by 31 October 2025 for the 2024-25 tax year. If you miss this but file online, you still have until 31 January 2026. Very few people now file paper returns — the online system is quicker and HMRC calculates your tax automatically.

31 January 2026

Online Tax Return + Balancing Payment

The most important deadline. You must: (a) submit your online self-assessment return for 2024-25, AND (b) pay any tax you owe for 2024-25 that is not covered by payments on account or PAYE deductions. This is called the "balancing payment". Both the return and payment are due on the same day.

31 January 2026 (same day)

First Payment on Account (2025-26)

Simultaneously with your 2024-25 balancing payment, your first payment on account toward the 2025-26 tax year is also due. This is 50% of your 2024-25 tax liability (excluding Class 2 NI and student loan repayments).

31 July 2026

Second Payment on Account (2025-26)

The second and final payment on account for 2025-26, also equal to 50% of your 2024-25 tax bill. After this, any remaining balance (or refund) is settled with your 2025-26 return in January 2027.

First-Year Exception: No Payments on Account in Year 1

If this is your first self-assessment tax return, you do NOT make payments on account when you file. You just pay your full 2024-25 tax bill by 31 January 2026. Payments on account start from your second year — if your first-year bill exceeds £1,000.

Payment on Account: Detailed Example

Understanding payments on account is one of the most confusing aspects of self-assessment for first-time filers. Here is a step-by-step example:

Scenario: Tax Bill of £8,000 for 2024-25

Assume Sarah's self-assessment for 2024-25 shows a total tax liability of £8,000 and less than 80% was deducted through PAYE. Payments on account apply:

31 Jan 2026

Balancing payment 2024-25
+ 1st POA 2025-26

£8,000 + £4,000 = £12,000

31 Jul 2026

2nd POA
2025-26

£4,000

31 Jan 2027

Balancing payment
2025-26 (if any)

Depends on actual 2025-26 bill

If Sarah's 2025-26 tax bill is also £8,000, she has already paid £8,000 on account — no balancing payment due. If it is £10,000, she pays £2,000 extra on 31 Jan 2027. If only £6,000, she receives a £2,000 refund.

When Payments on Account Do NOT Apply

You do not have to make payments on account if:

Your previous year's self-assessment tax bill was £1,000 or less
More than 80% of your tax was deducted at source (e.g. via PAYE)
You are completing self-assessment solely to claim a tax refund

How to Register for Self-Assessment

For the Self-Employed (Sole Trader)

Go to gov.uk/register-for-self-assessment
Select "I am self-employed"
Create or log in to your Government Gateway account
Complete the CWF1 form online (you can also post it)
HMRC will post your Unique Taxpayer Reference (UTR) within 10 working days (21 days if abroad)
Activate your HMRC online account when you receive your activation code by post (can take 7 days)

Start Early — UTR Takes Up to 21 Days

The registration process can take up to 3-4 weeks to complete by the time you receive your UTR and then activate your online account. Do not leave registration until October — apply as soon as you know you need to file a return, ideally in April or May after the tax year ends.

The SA100 Self-Assessment Form Explained

The main SA100 form collects information about your income from all sources. Most people file online rather than using the paper form, but the information required is identical. Key supplementary sections include:

SA103S / SA103F: Self-employment income (short or full version)
SA105: UK property income (rental)
SA106: Foreign income
SA108: Capital gains
SA109: Residence and remittance basis
SA102: Employment income (in addition to PAYE)

Making Tax Digital for Income Tax (MTD ITSA)

Making Tax Digital is HMRC's programme to modernise the tax system. From April 2026, self-employed people and landlords with combined income over £50,000 must keep digital records and submit quarterly updates rather than just an annual return:

Apr 2026

MTD ITSA Phase 1

Sole traders and landlords with income over £50,000 must use MTD-compatible software and submit quarterly updates.

Apr 2027

MTD ITSA Phase 2

Extended to those with income between £30,000 and £50,000.

TBC

MTD ITSA Phase 3

Those with income between £20,000 and £30,000 — date not yet confirmed.

Budget Payment Plans

HMRC offers a Budget Payment Plan that lets you spread your self-assessment tax bill with regular weekly or monthly payments throughout the year. This is different from a Time-to-Pay arrangement (which is for when you cannot pay). You set it up via your HMRC online account and can start, stop, or change amounts at any time.

For example, if you expect to owe approximately £6,000 for 2025-26, you could set up £500/month from April 2025, accumulating £6,000 by the January 2026 deadline — avoiding any lump-sum pressure. Overpayments earn HMRC repayment supplement.

Frequently Asked Questions

Who needs to complete a self-assessment tax return?

You need to complete a self-assessment return if you: are self-employed with income over £1,000; are a company director; earned over £100,000; received untaxed income over £2,500; claim Child Benefit and you or your partner earned over £60,000; had rental income; received foreign income; or had capital gains above £3,000. HMRC can also issue a notice requiring you to complete a return even if none of these apply.

When is the self-assessment registration deadline for 2024-25?

The registration deadline for the 2024-25 tax year (ended 5 April 2025) is 5 October 2025. If you were already registered for previous years, you do not need to re-register. Only new self-assessment taxpayers — or those who have not filed for several years and are now required to again — need to register.

Can I deregister from self-assessment?

Yes. If you are no longer required to complete a self-assessment return — for example, you have stopped being self-employed and have no other untaxed income — you can ask HMRC to remove you from the self-assessment system. Do this via your HMRC online account or by calling 0300 200 3310. You must ensure all outstanding returns and any tax owed are up to date first.

What is the difference between filing late and paying late?

Filing late (not submitting your return by 31 January) triggers an immediate £100 penalty regardless of whether you owe tax. Paying late (submitting the return but not paying by 31 January) attracts interest at ~7% per annum from 1 February, plus a 5% surcharge if unpaid after 30 days. You can receive both penalties simultaneously. Always file your return on time even if you cannot pay — it stops the late filing penalties accumulating.

What happens if I am registered but did not receive a tax return notice?

You are responsible for filing your return whether or not HMRC sends you a notice. If you are registered for self-assessment, the obligation to file by 31 January exists regardless. If you believe you no longer need to file (e.g. ceased being self-employed), contact HMRC to confirm before assuming you can stop. Filing unnecessarily is generally not penalised; not filing when required is.

What is Making Tax Digital for Income Tax Self-Assessment?

MTD ITSA requires self-employed people and landlords with qualifying income to keep digital records using HMRC-approved software and submit quarterly summaries of income and expenses. The end-of-period statement and final declaration replace the annual SA return. Phase 1 starts April 2026 for those earning over £50,000; Phase 2 in April 2027 for £30,000–£50,000 earners.

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Mustafa Bilgic

UK self-assessment specialist. Deadline information verified against HMRC guidance, updated February 2026. Always check current deadlines at gov.uk/self-assessment-tax-returns.