UK Income Tax for individuals: the SA100 Self Assessment return
UK Income Tax for individuals filing the SA100 Self Assessment return: who must register and file, rates and bands for England, Wales and Northern Ireland, the Personal Allowance taper, savings and dividend allowances, Finance Act 2026 rate changes, High Income Child Benefit Charge, Marriage Allowance, pension and Gift Aid relief, payments on account, deadlines, penalties and interest, with a dated section for the 2025/26 return now being filed.
Applicable period 2026Built by Michael Cutajar and the OpenAccountants team· Last updated Sep 26, 2026
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Key figures — United Kingdom, 2026
Band (standard Personal Allowance)
2025/26
2026/27 (current year)
Personal Allowance
Up to £12,570 at 0%
Up to £12,570 at 0%
Basic rate 20%
£12,571 to £50,270
£12,571 to £50,270
Higher rate 40%
£50,271 to £125,140
£50,271 to £125,140
Additional rate 45%
Over £125,140
Over £125,140
The full Guide
Tax year 2026/27 (6 April 2026 to 5 April 2027) is the year in force. The returns being filed now are for tax year 2025/26, on the SA100 form HMRC calls "Tax Return 2026", which is due online by 31 January 2027. Where a rule differs between those years, both are shown. Changes already enacted for 2027/28 are flagged so that nobody applies them early.
Scope and who this is for
This guide covers individuals resident in England, Wales or Northern Ireland who work out Income Tax on the SA100 return. It covers who must register and file, rates and bands, the Personal Allowance taper, the savings and dividend allowances, the Finance Act 2026 rate changes, the High Income Child Benefit Charge, Marriage Allowance, pension and Gift Aid relief claimed through the return, payments on account, deadlines, penalties and interest.
Out of scope: Scottish taxpayers (the rates are different, so refer them); non-residents and split years (SA109); the foreign income and gains regime; trusts (SA107); Capital Gains Tax (SA108); the detail of self-employment (SA103) and UK property (SA105); National Insurance. Making Tax Digital for Income Tax (MTD) gets a cross-reference only (MTD: who needs it).
Ask the client first
Which tax year is this: the 2025/26 return being filed now, or planning for 2026/27?
Where was your main home during the year? If it was in Scotland, stop and refer. If you were outside the UK for part of the year, also refer.
Have you registered for Self Assessment before? Did you get a return for 2024/25? (This decides the 5 October registration duty.)
Employment: P60, P11D, P45, any tips or payments not on the P60, any termination or redundancy payment?
Self-employment or property: gross income before expenses? (This decides the trading and property allowances and MTD.)
Bank and building society interest, including taxed and untaxed interest, but not ISA interest.
Dividends from UK companies and funds, and any non-ISA share holdings.
Pensions received: State Pension, workplace or private pensions, annuities.
Personal pension contributions: relief at source or net pay? Contributions paid gross? Have you taken flexible pension income before?
Gift Aid donations, and any made since 6 April of the current year that you want carried back.
Married or in a civil partnership? What are both partners' incomes? Is Marriage Allowance already in place?
Does anyone in the household get Child Benefit? What is each partner's adjusted net income?
Did you get a Winter Fuel Payment in 2025/26?
What did your last SA302 say, and which payments on account did you make on 31 January and 31 July?
Has HMRC written to you about MTD?
The method, step by step
Pick the tax year and confirm the person is in scope. For a Scottish taxpayer, a non-resident or a split year, stop and refer.
Decide whether a return is needed and whether the 5 October registration deadline has been missed (who must send a return; register).
Collect total income by source, gross. Non-savings income is employment, self-employment, pensions and property. Savings income is interest. Dividend income comes last.
Take off reliefs deductible from income, such as trading losses and pension contributions paid gross. Then work out adjusted net income by also deducting grossed-up Gift Aid and grossed-up relief-at-source pension contributions (adjusted net income).
Set the Personal Allowance. Start at £12,570 and taper it by £1 for every £2 of adjusted net income above £100,000 (Income Tax rates). Adjust for Marriage Allowance if the client is the transferor.
Extend the basic rate band by grossed-up relief-at-source pension contributions and grossed-up Gift Aid.
Tax the income in statutory order: non-savings first, then savings (starting rate, then Personal Savings Allowance), then dividends (dividend allowance). Use the rates for the chosen year.
Take off tax reducers, such as the Marriage Allowance reduction for the recipient.
Add charges: High Income Child Benefit Charge, any Winter Fuel Payment charge for 2025/26, and the pension annual allowance charge.
Take off tax already paid: PAYE, tax taken off interest, and payments on account made.
Work out payments on account for the next year, then set the 31 January and 31 July dates (payments on account).
File and pay on time. A late return or late payment triggers the penalties and interest below.
For 2026/27, Finance Act 2026 s.2 sets "the basic rate is 20%", "the higher rate is 40%" and "the additional rate is 45%".
"You do not get a Personal Allowance on taxable income over £125,140" (Income Tax rates).
Scotland: "Income tax bands are different if you live in Scotland". Scottish rates apply to non-savings income only; savings and dividends use UK rates (Income Tax in Scotland). This guide refers Scottish taxpayers; see "When to refuse or refer".
The Personal Allowance is £12,570 and the basic rate limit is £37,700 for every tax year up to and including 2030/31. FA 2026 s.10 extended the freeze in FA 2021 s.5 from 2027/28 to 2030/31. With a standard allowance, higher rate therefore starts above £50,270 until then.
The starting rate limit for savings is £5,000 for 2026/27 to 2030/31 (s.9), and indexation is switched off.
Personal Savings Allowance: additional rate taxpayer
£0
£0
Not yet published
For 2025/26 the policy paper says "Since April 2017 the rates have been 20% for basic rate taxpayers, 40% for higher rate taxpayers, and 45% for additional rate taxpayers". FA 2026 s.3(2) keeps them for 2026/27.
The savings increase is for 2027/28, not 2026/27. FA 2026 s.5: "For the tax year 2027-28 ... the savings basic rate is 22% ... higher rate is 42% ... additional rate is 47%." These rates apply UK-wide.
Personal Savings Allowance amounts are from HMRC's current guidance. HMRC has not published 2027/28 amounts.
FA 2026 s.4 substitutes "10.75%" for "8.75%" and "35.75%" for "33.75%", with "effect for the tax year 2026-27 and subsequent tax years". The policy paper confirms "the dividend additional rate will remain at 39.35%". The rates apply UK-wide, including to Scottish taxpayers.
The rise applies to distributions made on or after 6 April 2026. A 2025/26 return uses 8.75% and 33.75%.
2025/26 and 2026/27: property profit is taxed at the main rates (20%, 40%, 45%).
2027/28: separate property rates of 22%, 42% and 47% apply in England, Wales and Northern Ireland (s.7). See the UK property (SA105) guide.
From 2027/28, general reliefs and allowances, including the Personal Allowance, are set against property, savings and dividend income only after other income. Do not apply this ordering to 2025/26 or 2026/27.
Transfer £1,260 of Personal Allowance; reduces partner's tax by up to £252
2025/26 and 2026/27
High Income Child Benefit Charge
Adjusted net income over £60,000; full charge at £80,000 or more; 1% per £200
2024/25 onwards
Pension annual allowance
£60,000
Current tax year
Tapered annual allowance
Threshold income over £200,000 and adjusted income over £260,000; minimum £10,000
Current tax year
Termination payments
Taxable above the £30,000 threshold only for a payment to which s.403 applies. Post-employment notice pay (ss.402A-402E), contractual PILON, holiday pay and bonuses are taxed in full as earnings (s.401; s.402B)
A return is required if, in the last tax year, the person "were self-employed as a 'sole trader' and earned more than £1,000 (before taking off anything you can claim tax relief on)", was a partner in a partnership, had Capital Gains Tax to pay, "had to pay the High Income Child Benefit Charge and do not pay it through PAYE", or is an off-payroll worker repaying a student or postgraduate loan.
A return may be needed for untaxed income: rent, tips and commission, savings interest, dividends, foreign income, or any taxable UK income of a non-resident. It may also be needed to claim some reliefs. A person HMRC has written to "must" send a return by the deadline on the letter.
Trading and property thresholds. Gross trading income of £1,000 or less, and gross property income of £1,000 or less, is covered by the allowances ("full relief"). HMRC must be told about "gross trading income over £1,000 — register for Self Assessment". Above £1,000 the person may deduct the £1,000 allowance instead of actual expenses ("partial relief"), but not both. The trading allowance does not apply to partnership income.
Property notification tiers: "gross property income over £1,000 up to £2,500 — contact HMRC"; "property income over £2,500 — register for Self Assessment".
Allowances cannot be used in a year with any trade or property income from "a company you or someone connected to you owns or controls", a partnership where you or someone connected to you are partners, or "your employer or the employer of your spouse or civil partner". The property allowance also cannot be used if you "claim the tax reducer for finance costs", or if you deduct expenses from letting a room in your own home instead of using Rent a Room.
Other income under the trading allowance (miscellaneous income such as casual services, for example babysitting or gardening, or hiring out personal equipment): HMRC says to contact it for "other gross income over £1,000 up to £2,500" and to register for Self Assessment for "other income over £2,500".
Register by 5 October. "You must tell HMRC by 5 October 2026 if you need to complete a tax return for the previous tax year" (2025/26) and you have not sent a return before, or did not need to send one for 2024/25. Registering late can lead to a failure-to-notify penalty if the tax is not paid by 31 January.
The standard Personal Allowance is £12,570. It "goes down by £1 for every £2 that your adjusted net income is above £100,000", so it is zero at £125,140 or above. This applies "regardless of your date of birth".
Adjusted net income is total taxable income, less trading losses and pension contributions paid gross, less grossed-up Gift Aid ("for every £1 of Gift Aid donations you made, take £1.25"), and less grossed-up relief-at-source pension contributions (also £1.25 per £1). Add back any trade union or police organisation relief (up to £100) taken at step 1.
Pension contributions and Gift Aid can bring adjusted net income back under £100,000 and restore the allowance. Check the contribution fits the annual allowance.
Order: any unused Personal Allowance first, then the starting rate for savings, then the Personal Savings Allowance, then the savings rates.
Starting rate for savings: available if other taxable income (not savings or dividends) "is less than £17,570". It gives up to £5,000 of interest tax-free, reduced £1 for every £1 of other income above the Personal Allowance.
Personal Savings Allowance: £1,000 for basic rate, £500 for higher rate, £0 for additional rate. "To work out your tax band, add all the interest you've earned to your other income." Interest above the allowance is taxed at the savings rates.
ISA interest is not taxable. Joint account interest is split equally unless shown otherwise.
Dividends sit on top of all other income. First, dividends within any unused Personal Allowance are tax-free. Then the £500 dividend allowance applies. Then 10.75% (ordinary), 35.75% (upper) or 39.35% (additional) for 2026/27.
The allowance is a band taxed at nothing, not a deduction. Dividends inside it still count toward the basic and higher rate bands. The SA150 notes say to include all dividend income "even if it's less than £500".
ISA dividends are not taxable. Dividends above both the unused Personal Allowance and the dividend allowance must be reported.
The charge applies if you or your partner gets Child Benefit and an adjusted net income is "over £60,000 for tax years starting from 2024 to 2025". It is "1% of your Child Benefit for every £200" above £60,000, and all of it at "£80,000 or more".
If both partners are over the threshold, "whoever has the higher income is responsible". 'Partner' includes an unmarried partner living with you. The charge may also apply "if someone else gets Child Benefit for a child living with you and they contribute at least an equal amount towards the child's upkeep". "It does not matter if the child living with you is not your own child."
You can pay through PAYE, but you must use Self Assessment if you need a return for another reason, or if it is later than 31 January after the tax year. For example, a 2025/26 charge not settled by 31 January 2027 must go through Self Assessment.
Opting out of Child Benefit payments avoids the charge but keeps National Insurance credits.
The lower earner transfers £1,260 of Personal Allowance to a spouse or civil partner, which "reduces their tax by up to £252".
All of these conditions must be met: married or in a civil partnership (not just living together); the transferor pays no Income Tax or has income below the Personal Allowance; the recipient pays basic rate, "which usually means their income is between £12,571 and £50,270". A Scottish recipient may pay starter, basic or intermediate rate.
Claims can be backdated "to 6 April 2022 (the 2022 to 2023 tax year)". The transfer renews automatically until cancelled. It cannot be combined with Married Couple's Allowance.
In the 2025/26 SA150 notes, the Marriage Allowance section is for a transferor whose "earnings from 6 April 2025 to 5 April 2026 were less than £12,570 (plus up to £6,000 in savings interest)". A claim under the foreign income and gains regime for 2025/26 loses the entitlement (SA150 notes 2026).
Net pay schemes: relief is given through payroll, so there is nothing to claim.
Relief at source (personal and stakeholder pensions, some workplace schemes): the provider adds 20% basic rate relief. On the return, enter the gross amount (the net paid multiplied by 100/80). The gross amount extends the basic rate band and reduces adjusted net income. A higher or additional rate taxpayer in England, Wales or Northern Ireland claims "20% up to the amount of any income you have paid 40% tax on" and "25% up to the amount of any income you have paid 45% tax on".
Relief is limited to contributions up to 100% of annual earnings. A non-taxpayer gets relief at source up to £2,880 of net contributions if they have no earnings.
Annual allowance of £60,000. It is lower after flexible access (the money purchase annual allowance) or with high income (the taper). Unused allowance from the previous 3 tax years can be carried forward. Any charge is reported in the 'Pension savings tax charges' section (SA101 on paper).
The charity claims 25p per £1. A higher rate taxpayer claims the difference on the return. HMRC's example: "You donate £100 ... make your donation £125. You pay 40% tax so you can personally claim back £25.00 (£125 x 20%)."
Donations must not exceed "4 times what you have paid in tax in that tax year". Otherwise HMRC may recover the shortfall.
Donations made in the current year, up to the filing date, can be treated as made in the previous year. This is lost if you "miss the deadline for your Self Assessment tax return (31 January if you file online, or 31 October if you file by post)".
Two payments, each normally half of last year's Self Assessment liability, are due "by midnight on 31 January and 31 July". The liability used is the net amount after tax deducted at source; it includes Class 4 National Insurance.
They are not required if either: "the amount of tax you owed last year was less than £1,000", or "last year you paid more than 80% of the tax you owed outside of Self Assessment" (PAYE, tax taken off interest).
The balancing payment (total tax for the year less the payments on account made) is due "by midnight on 31 January the following year", together with the first payment on account for the next year.
To reduce payments on account, apply online or on form SA303. If the bill turns out higher, "you'll be charged interest on the difference".
The 2026/27 payments on account are based on 2025/26 liability. The 2026/27 dividend rate rise can leave a larger balancing payment on 31 January 2028.
Salary £35,000, PAYE £4,486, no other income. Taxable income is £35,000 − £12,570 = £22,430. Tax at 20% is £4,486. After PAYE, nothing is due. The result is the same for 2025/26: HMRC's own example taxes "£22,430 (£35,000 minus £12,570)" at 20%. No return is needed for this income alone.
Employment £40,000 (PAYE £5,486), self-employment profit £20,000, UK dividends £5,000. Total income is £65,000 and adjusted net income is under £100,000, so the full £12,570 allowance applies.
Non-savings income: £60,000 − £12,570 = £47,430 taxable. £37,700 at 20% = £7,540. £9,730 at 40% = £3,892. Non-savings tax is £11,432.
Dividends sit wholly in the higher rate band. The first £500 is taxed at nothing; the remaining £4,500 is taxed at the upper rate.
2025/26 return: £4,500 × 33.75% = £1,518.75. Total Income Tax is £12,950.75. Less PAYE £5,486 leaves £7,464.75 through Self Assessment.
2026/27: £4,500 × 35.75% = £1,608.75. Total Income Tax is £13,040.75. Less PAYE £5,486 leaves £7,554.75, which is £90 more.
Class 4 National Insurance on the profit is extra (see the SA103 guide), and it also feeds payments on account.
Total income £115,000, all non-savings. Relief-at-source pension contributions are £8,000 paid, which is £10,000 gross. Adjusted net income is £115,000 − £10,000 = £105,000. The allowance falls by (£105,000 − £100,000) / 2 = £2,500, to £10,070. The basic rate band is extended by the gross contribution: £37,700 + £10,000 = £47,700. Higher rate therefore starts above £10,070 + £47,700 = £57,770 of income. Without the contribution, adjusted net income would be £115,000 and the allowance would be £12,570 − £7,500 = £5,070.
The higher-earning partner has adjusted net income of £70,000; the other partner's is lower. Assume Child Benefit received in the year was £1,800 (the actual figure comes from the family's award). £70,000 − £60,000 = £10,000 over the threshold. £10,000 / £200 = 50, so the charge is 50% × £1,800 = £900, payable by the higher earner. HMRC's own example: adjusted net income of £67,600 gives "38%".
HMRC's example: the lower earner has £11,500 of income and the partner has £20,000. Before the transfer the couple pays tax on £7,430. After transferring £1,260, the lower earner's allowance is £11,310, so they pay tax on £190. The partner is taxed on £6,170. "As a couple you benefit, as you are only paying Income Tax on £6,360 rather than £7,430, which saves you £214 in tax."
Starting rate: wages £16,000 and interest £200. £16,000 − £12,570 = £3,430 reduces the starting rate band to £5,000 − £3,430 = £1,570, so the £200 is tax-free.
Personal Savings Allowance: a basic rate taxpayer with £1,300 of interest. The first £1,000 is tax-free; £300 × 20% = £60. The rate is still 20% in 2026/27; 22% applies only from 2027/28.
Case G: first-year payments on account, 2025/26 return (payments on account)
Employee with rental profit, filing for the first time. 2025/26 Income Tax is £13,000 and PAYE is £5,000, so £8,000 is owed through Self Assessment. That is at least £1,000, and far less than 80% was paid at source, so payments on account apply. By 31 January 2027 the client pays the £8,000 plus a first 2026/27 payment on account of £4,000, a total of £12,000. A second £4,000 is due by 31 July 2027. Any 2026/27 balance is due by 31 January 2028.
Case H: late online return for 2025/26 (penalties)
The return is filed on 20 August 2027 with £4,000 of tax due, which was paid on 31 January 2027. Late filing penalties: £100, plus £10 a day for 90 days (£900, the maximum), plus the 6-month penalty of the greater of 5% × £4,000 = £200 and £300, so £300. The total is £1,300. Had the tax also been paid late, 5% penalties at 30 days, 6 months and 12 months would be added, plus interest.
When to refuse or refer
Scottish taxpayers (main home in Scotland, or unclear between homes): refer. The 2026/27 Scottish bands are 19%, 20%, 21%, 42%, 45% and 48% at different thresholds. Pension relief and Marriage Allowance limits also differ (Income Tax in Scotland).
Non-residents, split years, dual residents and the foreign income and gains regime (which replaced the remittance basis from 6 April 2025): refer to a specialist and the SA109 pages.
Trust or estate income (SA107), capital gains (SA108) and partnership returns: out of scope.
Pensions: the tapered or money purchase annual allowance, carry-forward near the limit, annual allowance charges, lump sums and drawdown. Refer (annual allowance).
Termination and redundancy payments: refer, whatever the size, if the payment includes notice pay or PILON, if its make-up is unclear, if it is over the £30,000 threshold, or if it has non-cash elements (ITEPA 2003 s.403; s.401).
Anyone asking to apply 2027/28 savings or property rates, or the new allowance order, to 2025/26 or 2026/27: refuse. Those rules are not in force until 6 April 2027.
MTD for Income Tax clients: the quarterly updates and digital records are outside this guide. See the Making Tax Digital guide.
Disputes, enquiries, penalty appeals and reasonable excuse: refer.
Never present a computation as final. It is an estimate until checked against the SA302 or HMRC's calculation.
Late filing: "an initial £100 penalty". After 3 months, "additional daily penalties of £10 per day, up to a maximum of £900". After 6 months, "a further penalty of 5% of the tax due or £300, whichever is greater". After 12 months, "another 5% or £300 charge, whichever is greater". All partners are charged if a partnership return is late.
Late payment: "penalties of 5% of the tax unpaid at: 30 days 6 months 12 months", plus interest.
Late registration: a failure-to-notify penalty can apply if you register after 5 October and do not pay all the tax by 31 January.
A penalty is payable within 30 days of the notice. Appeals need a reasonable excuse.
Late payment interest is "set at base rate plus 4% from 6 April 2025 (was plus 2.5% on or before 5 April 2025)" and is charged on tax paid late.
The current rate on HMRC's page is "7.75% from 9 January 2026". Repayment interest is "2.75% from 9 January 2026". The rate moves with Bank of England base rate, so check the page on the day.
Sole traders and landlords with qualifying income over £50,000 for 2024/25 "should've started using Making Tax Digital for Income Tax from 6 April 2026". The threshold is over £30,000 (2025/26 income) from 6 April 2027 and over £20,000 (2026/27 income) from 6 April 2028. Partnerships come later.
A 2025/26 SA100 is still filed as normal. HMRC: "if you use Making Tax Digital for Income Tax from 6 April 2026, current penalties will apply to your 2025 to 2026 tax return deadline of 31 January 2027".
From the year a person joins, new points-based late submission and late payment penalties replace the ones above. There are no penalties for missed quarterly updates in 2026/27. See the Making Tax Digital guide for details.
Tax year confirmed. The 2025/26 return uses dividend rates of 8.75%, 33.75% and 39.35%; 2026/27 uses 10.75%, 35.75% and 39.35%.
Residence confirmed; Scottish, non-resident and split-year cases referred.
Registration by 5 October checked for first-time filers.
Income split into non-savings, savings and dividends, and taxed in that order.
Adjusted net income worked out; Personal Allowance taper applied above £100,000.
Basic rate band extended for relief-at-source pensions and Gift Aid; higher rate relief claimed.
Starting rate for savings and Personal Savings Allowance applied by band; savings at 20%, 40% or 45%, not the 2027/28 rates.
£500 dividend allowance treated as a band, not a deduction.
Marriage Allowance conditions checked on both partners.
Child Benefit charge worked out for the higher-income partner if over £60,000.
Winter Fuel Payment charge considered on the 2025/26 return.
PAYE and tax deducted at source taken off; payments on account made taken off.
Next year's payments on account worked out (the £1,000 and 80% tests); SA303 considered only with evidence.
Filed by 31 January 2027 online, or by 31 October 2026 on paper; payment dates given to the client.
MTD status checked for 2026/27 onwards.
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