Exam Marker & Invigilator Tax UK 2026/27: Second Income and Tax Codes Explained
Teachers and others who mark exams or invigilate for exam boards on top of a main job need to understand how this second income is taxed. Full worked example on £2,500 of marking income alongside a main salary.
Two different payment structures, one tax principle
Exam marking and invigilation sit in an unusual spot: some exam boards engage markers as self-employed contractors, paying gross and expecting the marker to declare the income via Self Assessment; others (and most in-school invigilation work) run this through casual PAYE, deducting tax at source like any other employment. Either way, the underlying tax principle is the same — it's additional income taxed on top of whatever your main job already uses up in Personal Allowance and basic-rate band.
Self-Employed Tax Calculator
Calculate income tax, Class 2 and Class 4 National Insurance for self-employed and sole traders for 2025/26.
Open Self-Employed Tax calculatorWorked example: £2,500 marking income, already a basic-rate taxpayer
Assuming a main salary already fully uses the Personal Allowance and keeps total income within the basic-rate band:
Income tax on marking income: £2,500 × 20% = £500
Class 4 NI (if paid as self-employed, combined with any other self-employment): £2,500 × 6% = £150
Total additional tax and NI: £650
Net from marking income: £2,500 − £650 = £1,850
Take-Home Pay Calculator
Calculate your net salary after income tax, National Insurance and student loan deductions.
Open Take-Home Pay calculatorWhy the marginal-rate point catches people out
A common misconception is that a small amount of extra income like exam marking "gets its own allowance" — it doesn't. If your main job already uses your full Personal Allowance and pushes you into (or through) the basic-rate band, every pound of marking income is taxed at whatever your marginal rate already is, which for many experienced teachers and other professionals doing marking on the side means the higher rate (40%) applies to some or all of it, not the 20% many assume by default.
Deductible expenses (self-employed markers only)
- A proportion of home-office costs for hours spent marking
- Printing, stationery, postage if not provided by the exam board
- Travel to required standardisation or training sessions
- A proportion of a computer/laptop used for online marking platforms
Filing and paying
If paid as a self-employed contractor, register for Self Assessment once total self-employment income exceeds £1,000, and file online by 31 January following the tax year end, declaring the marking income alongside your main employment income. If paid via casual PAYE, tax is deducted automatically and no separate filing is generally needed unless you have other reasons to file.
uk-national-insurance-contributions-guideFrequently asked questions
Is exam marking income taxed differently from a main teaching salary?
It depends on how the exam board engages you. Many exam boards pay markers as self-employed contractors (no PAYE deducted, income declared via Self Assessment), while invigilators booked through an agency or school are often paid as casual employees with PAYE applied. Either way, the income is taxable — the difference is just in how and when the tax is collected.
Do I need to register as self-employed just for occasional exam marking?
Yes, if the exam board pays you as a self-employed contractor and your total self-employment income (marking plus any other self-employed work) exceeds £1,000 in a tax year, you need to register for Self Assessment and declare it, even though it's a modest amount on top of a main job.
How is exam marking income taxed if I'm already a higher-rate taxpayer from my main job?
Additional self-employed or casual income on top of an existing salary is simply taxed at your marginal rate — if your main job already uses up your Personal Allowance and basic-rate band, marking income taxed through Self Assessment would be taxed at 40% (or 45% if it pushes you into the additional rate), since there's no fresh allowance for a second stream of income.
How much tax would a basic-rate taxpayer pay on £2,500 of exam marking income?
If your main salary already uses your Personal Allowance and keeps you as a basic-rate taxpayer, the additional £2,500 would be taxed at 20% income tax (£500) plus Class 4 NI at 6% if self-employed (£150 additional, since Class 4 is calculated on total self-employed profit above the lower profits limit combined with other self-employment) — in practice, most marking income sits within the basic-rate band and adds a fairly modest, predictable extra tax cost.
Can exam markers claim any expenses?
Self-employed markers can claim genuine costs directly related to the marking work — a proportion of home-office costs for the hours spent marking, printing/stationery if not provided, and travel to any required standardisation or training sessions. Employed invigilators paid via PAYE generally have fewer expense-claim opportunities since employment expense rules are stricter.
Try the calculators
Related reading
Agency Care Worker Tax UK 2026/27: Multiple Payslips, NI and Mileage
Care workers placed by agencies with multiple clients or care homes often get several payslips a month. Full worked example on £24,000 income and how mileage between visits is treated.
Council Refuse Collector Pay & Tax UK 2026/27: Bin Lorry Crew Take-Home Explained
Refuse collectors are PAYE local authority (or contractor) employees with early starts, physically demanding shifts and often good overtime and pension provision. Full worked example on take-home pay and shift allowances for 2026/27.
Nanny & Au Pair Tax UK 2026/27: Why Most Nannies Are Employees, Not Self-Employed
Most nannies are employees of the family they work for, not self-employed contractors, which changes who pays tax and NI. Full worked example on a £28,000 nanny salary.