Banding every year of service at your leaving age. The multiplier belongs to the age you were during each individual year, counted backwards from your last day, not to your age when you left. Priya above is 45 with ten years in, and only the four years from 41 onwards earn a week and a half; the other six earn one week each, giving 12 weeks rather than the 15 weeks a leaving-age multiplication reports. The error runs one way — always an overpayment — and it catches everyone who crossed 22 or 41 while employed.
Capping notice and holiday pay at £751. The weekly cap applies only to the section 162 redundancy calculation and reaches nothing else in your package. Notice pay, holiday pay, enhanced redundancy and ex-gratia sums are all worked out on actual pay with no ceiling at all. Applying £751 across the whole package understates David's notice entitlement above by £5,388.00, and the cap's scope is worth checking on any tool you are given — section 227 sets the limit and names the calculations it applies to, and neither statutory notice under section 86 nor holiday pay under the Working Time Regulations is among them.
Rounding your service up to the next year. Only complete years count, so nine years and eleven months is nine years and buys a week and a half less than most people expect. Continuous service also runs from the date your employment started, not from a promotion, a change of contract or a move between sites for the same employer. Enter your real start date and last day above and let the arithmetic do the truncating — the gap between what people assume and what the dates give is usually one whole year.
Applying the £30,000 exemption to each payment separately. HMRC aggregates first and exempts once: "Some payments and benefits must be added together before applying the threshold, producing an aggregate" (EIM13505). Statutory redundancy, an enhanced top-up and an ex-gratia sum are one award sharing one £30,000, not three. A tool that exempts the threshold from each component reports Marcus's £90,000.00 award as entirely tax-free, when £60,000.00 of it is chargeable.
Expecting National Insurance to appear beside the tax on the excess. Your final payslip will show income tax taken from the taxable slice of the award with nothing beside it in the deductions column, which reads like a payroll error and is not. Use it as a way to audit the payslip line by line: the notice and holiday rows should each show your usual deduction, and the redundancy row should show none at all. Anything taken from the redundancy row is worth querying with payroll. What the business itself owes on the same package is a separate question, answered below.
Averaging the wrong twelve weeks when your pay varies. The averaging window ends when redundancy notice was given, not when you actually left. Where notice was long, or where hours were cut during it, the two produce materially different weekly figures and the later window is the wrong one. Acas frames it as your average over a twelve-week period; gov.uk anchors that period to the notice date. If your hours dropped after notice, the reference period that matters closed before the drop.
Using sick pay, maternity pay or any reduced rate as your weekly figure. If you are on statutory sick pay or maternity pay when redundancy arrives, your week's pay for the calculation is your full normal pay, not the reduced rate on your current payslip. Entering the reduced figure can cut a statutory entitlement by a third or more. Use the pay you would have received working normally, before any reduction that was not a permanent change to your contract — the same protection historically covered furlough, where gov.uk was explicit that "your full normal pay must be used for the redundancy payment calculation".
Missing the Personal Allowance taper on a large settlement. A taxable excess that carries total income past £100,000 removes £1 of Personal Allowance for every £2 over, so each additional pound between there and £125,140 costs 60p in England, Wales and Northern Ireland and 67.5p under the Scottish advanced rate. The band rate on its own understates the bill badly in that zone. This calculator applies the taper to your whole year, which is why the tax figure moves when you change the pay-to-date box.
Assuming Northern Ireland uses the Great Britain caps. This calculator applies the Great Britain figures; Northern Ireland's caps are higher and legislated separately — the regional section above carries the current figures and the nidirect link.