Income Tax is charged on your salary after your Personal Allowance, and after any pension taken before tax. National Insurance is worked out on what you earn each month rather than across the year, because that is how it is actually assessed — so the annual figure here is twelve monthly calculations added together, not one yearly one. The two are not the same: the monthly threshold multiplied by twelve does not equal the annual threshold.

Student loan repayments work the same way and are rounded down to whole pounds each month. A postgraduate loan is repaid on top of any other plan, not instead of it.

• Before tax (net pay) — the contribution comes off before Income Tax, but not before National Insurance.
• Salary sacrifice — you give up the salary itself, so it escapes both Income Tax and National Insurance.
• After tax (relief at source) — the contribution leaves your pay after everything else, and your provider claims basic-rate relief on top, so 80% of it comes out of your take-home.

Above £100,000 the Personal Allowance is withdrawn by £1 for every £2 of income, which is why the band between £100,000 and £125,140 costs more in tax than the rate alone suggests.

What this does not cover

It assumes a standard tax code, that you are paid monthly, and that you are under State Pension age. It does not handle Marriage Allowance, Blind Person's Allowance, company cars or other benefits in kind, a salary that changes part-way through the year, or the higher-rate relief a higher-rate taxpayer claims back on a relief-at-source pension.

Where these rates come from

Every figure above is read from a dated rate file rather than written into the page, and each entry records the gov.uk page it came from. See Income Tax rates and Personal Allowances, Scottish Income Tax and rates and thresholds for employers on gov.uk.