Working out your own tax takes four lines, and doing it once by hand is the best defence against a wrong payslip. On a £34,000 salary in 2026/27: allowance off, £21,430 taxed at basic rate = £4,286.00; NI on pay above the threshold = £1,714.40; take-home £27,999.60. The same four lines, with your figure, are what the calculator linked below automates.
Line one and two: the allowance, then the bands
Start from taxable income: gross minus the £12,570 personal allowance (which shrinks by £1 for every £2 of income over £100,000, vanishing at £125,140). The first £37,700 of taxable income pays 20%, the slice up to £125,140 pays 40%, and everything above pays 45%. On £34,000 that is one band only: £21,430 × 20% = £4,286.00. These are the published GOV.UK figures the sources below carry: check your sums against them, not against a remembered rate.
Line three: National Insurance, on a different base
Employee NI ignores the personal-allowance taper and bands: it charges 8% on earnings between £12,570 and £50,270 and 2% above. On £34,000: (£34,000 − £12,570) × 8% = £1,714.40. NI is assessed per pay period on a real payslip, so a bonus month can pay a little less NI than an annual view predicts: pennies to a few pounds on a level salary, which is why annual calculators state the assumption.
Line four: what changes the answer for you
Pension by salary sacrifice or net-pay arrangement comes off before the tax is worked out. 5% on £34,000 removes £1,700 from the taxable figure and saves £476.00 of combined tax and NI. A student loan adds 9% above its plan threshold. A company benefit adds its cash equivalent to taxable pay through your code. Each one changes a LINE, not the method: set them in the calculator and read the recomputed net beside your payslip.
Questions people ask about work out my tax
Why does my tax code matter if the bands are fixed?
The code carries your allowance (1257L is the standard £12,570) plus any adjustments for benefits or owed tax. A wrong code taxes the right salary wrongly: the method above with the standard allowance is your cross-check.
Do I pay tax on the whole salary if I cross a band?
No: only the slice inside each band pays that band's rate. Crossing £50,270 by £100 costs 42% of that £100, nothing more.
Is this the same as Self Assessment?
Same tax, different collection. This page is the employee PAYE arithmetic; filing obligations and other income belong to a return, which this site deliberately does not advise on.