The Complete UK Tax Guide for Employees 2026/27

1. The UK tax system in 60 seconds

The UK has two main employment-related taxes: income tax (a percentage of your earnings above the personal allowance) and National Insurance (a separate percentage that funds State Pension and benefits). For most UK employees, both are deducted automatically from your salary through PAYE — Pay As You Earn. You don't usually file a tax return; HMRC reconciles annually using your employer's data.

UK tax law is complex but most of the complexity doesn't apply to most people. If you have a single job, no benefits in kind, no investment income above £1,000, no rental property, and no foreign income, your tax position is simple: PAYE handles everything, you'll see your numbers on the P60 each May, and you'll never need to file Self Assessment.

The complexity arrives when circumstances change: starting a second job, becoming self-employed, becoming a director, earning above £100,000, leaving the UK, or receiving significant untaxed income. This guide covers the cases that actually come up.

2. UK income tax bands and thresholds 2026/27

UK income tax (England, Wales, Northern Ireland) in 2026/27:

Scottish taxpayers use different bands: starter rate 19%, basic 20%, intermediate 21%, higher 42%, advanced 45%, top 48%. See full Scottish bands here.

See the UK Take-Home Pay Calculator for net pay at any salary, including Scotland mode.

3. National Insurance explained

National Insurance (NI) is a separate tax that funds State Pension and certain benefits. UK employees pay Class 1 NI via PAYE; self-employed pay Class 2 + Class 4 via Self Assessment.

Employees (Class 1) in 2026/27: 8% on earnings between £12,570 and £50,270; 2% above £50,270. Below £12,570 (the Primary Threshold), no NI is owed. You do still build State Pension qualifying years if you earn at least £125/week.

Self-employed (Class 2 + 4) in 2026/27: Class 2 is £3.45/week if profits exceed £6,725 (technically optional since 2024 but worth paying for State Pension qualifying years). Class 4 is 6% on profits £12,570-£50,270 then 2% above. See UK Self-Employed Tax Calculator.

Employers (Class 1 Secondary) in 2026/27: 15% on staff earnings above £5,000 (the Secondary Threshold was lowered from £9,100 in April 2025). This affects total cost-of-employment but doesn't appear on your payslip — your employer pays this on top of your gross salary.

4. UK tax codes — what they mean

Your tax code tells your employer how much personal allowance to apply when calculating tax. The standard 2026/27 code is 1257L (£12,570 allowance, standard treatment). Other common codes:

• 1257L — standard, full personal allowance
• BR — basic rate, all income at 20% (typically second job)
• D0 — higher rate, all income at 40% (typically second job for higher earners)
• D1 — additional rate, all income at 45%
• 0T — no allowance, often temporary while HMRC catches up
• K codes — owed tax adjustment (BIK or underpaid tax)
• M / N — Marriage Allowance recipient / giver
• S1257L — standard Scottish code
• C1257L — standard Welsh code
• W1 / M1 — emergency code (each pay period treated independently)

See all 14 UK tax codes explained for full coverage.

5. Personal Allowance and the £100k taper

The personal allowance is £12,570 in 2026/27 — the amount you can earn tax-free. It's been frozen since 2021/22 and remains frozen until April 2028, meaning real-terms erosion of about 4% per year as inflation continues.

The £100k taper: earners between £100,000 and £125,140 lose £1 of personal allowance for every £2 of income over £100,000. By £125,140, the entire £12,570 allowance is gone. The effect: a 60% effective marginal tax rate in this band (20% basic loss + 40% higher rate). Pension contributions and salary sacrifice in this band save 60% — extraordinarily efficient.

High earners between £100k-£125k often use salary sacrifice into pension aggressively to bring taxable income below £100k, reclaiming the personal allowance. A £20,000 pension sacrifice for someone on £120k can save approximately £12,000 in tax — by far the most tax-efficient single move available to UK earners.

6. PAYE — how it works

PAYE (Pay As You Earn) is the UK's automatic deduction system for employees. Each pay period, your employer:

1. Calculates your pay-period taxable earnings (gross minus pre-tax deductions like pension contributions)
2. Applies your tax code to determine personal allowance for the period (usually 1/52 of annual allowance for weekly, 1/12 for monthly)
3. Calculates income tax using the applicable bands
4. Calculates National Insurance using the applicable bands
5. Deducts both from your gross pay and sends them to HMRC
6. Reports the totals to HMRC via Real Time Information (RTI) submissions

At year-end, HMRC reconciles all your PAYE data. If you've paid the right amount: nothing happens. If you've overpaid: you receive a P800 with a refund. If you've underpaid: you receive a P800 with the underpayment, usually recovered via tax code adjustment for the next year (e.g. K codes).

Most UK employees never deal with HMRC directly because PAYE handles the whole process. The exceptions: people with multiple income sources, BIK above the allowance, complex circumstances, or those required to file Self Assessment.

7. Self Assessment — when you need it

Self Assessment (the SA100 return) is required for people whose tax can't be fully calculated through PAYE alone. Most UK employees don't need to file. You DO need to file if you:

• Are self-employed as a sole trader with income over £1,000
• Are a partner in a partnership
• Are a company director required to file (most directors with significant non-PAYE income)
• Earn over £150,000 with complex circumstances
• Are a landlord with rental income above £1,000/year
• Have significant untaxed income — investment income above £10,000, foreign income, capital gains above the annual exemption
• Were specifically asked by HMRC to file (sometimes random selection)

Self Assessment requires a UTR (Unique Taxpayer Reference). The deadlines: paper return by 31 October following the tax year end; online by 31 January. Tax owed paid by 31 January. If your bill exceeds £1,000, payments on account apply for the next year.

See the full SA100 Self Assessment guide and our UK Self-Employed Tax Calculator.

8. UK tax allowances and reliefs 2026/27

Beyond the personal allowance, UK taxpayers have access to several tax-efficient allowances and reliefs:

• ISA Allowance — £20,000/year. Tax-free saving and investing across cash, stocks & shares, innovative finance, and Lifetime ISAs. Use it or lose it — doesn't carry forward.
• Pension Annual Allowance — £60,000. Combined employer + employee contributions. Tapers down to £10,000 for very high earners (over £260k income).
• Personal Savings Allowance — £1,000 / £500 / £0. Tax-free interest on savings (basic rate / higher rate / additional rate taxpayers).
• Dividend Allowance — £500. Tax-free dividend income before rates apply.
• Capital Gains Annual Exemption — £3,000. Tax-free capital gains. Reduced from £12,300 in 2023.
• Marriage Allowance — £1,260 transferable. 10% of personal allowance can be transferred between spouses. Saves up to £252/year. See M and N tax codes.
• Trading Allowance — £1,000. Small trading or property income tax-free without registering for Self Assessment.
• Salary Sacrifice. Pension, EV, cycle-to-work schemes that save tax + NI on sacrificed amounts. Calculate savings.

See the full UK Statutory Rates 2026/27 reference for all allowances and thresholds.

9. Special UK tax situations

Multiple jobs. Your personal allowance is allocated across one job (usually the highest-paying). The other job(s) typically get a BR code (20% on all earnings). If your combined income is under £50,270, this works correctly. Above that, ensure the allowance is on the right job to optimise.

Leaving the UK. File P85 after departure. You may be owed a refund for the partial tax year. Statutory Residence Test determines whether you remain UK tax resident.

Going self-employed. Register via CWF1 within 3 months. You'll receive a UTR and start filing Self Assessment annually.

Stopping work mid-year. If you don't expect to work again that year, file P50 4 weeks after stopping. Often results in a refund of unused personal allowance.

Receiving benefits in kind. Company car, private medical, etc. show up on a P11D after year-end. Tax on these benefits is usually recovered via tax code adjustment (often a K code).

10. UK HMRC forms you'll meet

The UK tax system has a finite set of forms and reference numbers you'll encounter. The most common:

• NINO — your National Insurance Number, your unique tax/social-security ID
• P60 — annual year-end tax summary, issued by 31 May
• P45 — issued when leaving an employer; give to next employer
• P11D — benefits-in-kind summary, issued by 6 July
• UTR — Unique Taxpayer Reference for Self Assessment
• SA100 — main Self Assessment tax return
• P800 — HMRC's tax reconciliation letter (refund or underpayment)
• Starter Checklist (P46) — when starting a job without a P45
• P85 — when leaving the UK
• P50 — refund when stopping work mid-year
• CWF1 — registering as self-employed

See full UK HMRC Forms Explained guide.

11. Important UK tax dates 2026/27

The four UK tax dates everyone should remember:

• 5 April — last day of the UK tax year. ISA, pension contribution deadlines.
• 31 May — P60 deadline. Your employer must issue your year-end summary.
• 31 January — online Self Assessment filing AND payment deadline.
• 31 July — second payment on account due (if you owe Self Assessment).

See the full UK Tax Year 2026/27 Calendar for every important date.

12. Free UK tax tools

See all 16 calculators at /free-tools/.