Employed and self-employed tax calculator 2026/27

Income tax is worked out on both incomes added together, with one Personal Allowance between them. On a job paying £30,000 and a profit of £15,000 — £45,000 together — that comes to £6,486.00. National Insurance is charged separately: £1,393.92 of Class 1 on the job and £145.80 of Class 4 on the profit, so £36,974.28 is left.

On the £30,000 job and £15,000 profit above, your job's payroll has already taken £4,879.92 of the £8,025.72 due. The rest — about £3,145.80 — is settled through Self Assessment, which is £262.15 a month if you put it by as you earn it. HMRC may also ask for payments on account towards next year's bill.

The allowance is shared between the two: whatever the job does not use is set against the profit. Your tax code usually gives the whole allowance to the job, so the profit is taxed from the first pound and the bill arrives with Self Assessment rather than through payroll.

There is. Where one person pays Class 1 on a job and Class 4 on a profit, regulation 100 of the Social Security (Contributions) Regulations 2001 sets an annual maximum on the two together, and it is the Class 4 that gives way — the Class 1 your payroll has taken is not touched. It is not only a high-earnings rule, and it does not wait for the profit to reach the upper profits limit of £50,270: the maximum starts to hold the Class 4 down as soon as the Class 1 charged at the main 8% and the Class 4 charged at the main 6% come to more than £2,262.00 between them, which is that 6% on the whole band between the two profits limits. The 2% charged on pay above the upper earnings limit is no part of that test, and because both incomes go into it there is no one salary and no one profit at which the maximum begins — the worked calculation above is what says whether it has bitten on the figures you typed. Where the profit is at or above £50,270 the reduction is two-thirds of the Class 1 charged at the main rate — give or take a penny, because the regulation rounds at two different points and this page follows it rather than the shorter sum — until no Class 4 is left at that rate; below that profit it is smaller than two-thirds, because there is less main-rate Class 4 for it to take. This calculator applies it. On the £30,000 job and £15,000 profit above it does not bite: the maximum is no lower than the £145.80 of Class 4 the percentages charge, so nothing is taken off it.