Most calculator sites ask you to trust them. We would rather show you the test results. Below is every known-answer check we run against Palarid's money maths — the expected value, the value our formulas computed, and where the expected value comes from.
Tests last executed: 31 July 2026 · Figures for the 2026/27 tax year
| Check | Expected | Computed | |
|---|---|---|---|
| £20,000 salary — income tax HMRC bands 2026/27 | £1,486.00 | £1,486.00 | PASS |
| £20,000 salary — National Insurance 8% between £12,570 and £50,270 | £594.40 | £594.40 | PASS |
| £50,270 (top of basic rate) — income tax 20% × £37,700 exactly | £7,540.00 | £7,540.00 | PASS |
| £60,000 — take-home pay worked example on the take-home page | £45,357.40 | £45,357.40 | PASS |
| £125,140 — allowance fully tapered £1 withdrawn per £2 above £100,000 | £42,516.00 | £42,516.00 | PASS |
| £150,000 — income tax additional rate 45% | £53,703.00 | £53,703.00 | PASS |
| Check | Expected | Computed | |
|---|---|---|---|
| £60,000 — Scottish income tax four bands engaged; working shown on the Scottish tax page | £13,213.80 | £13,213.80 | PASS |
| £30,318 — Scottish bill at the crossover the point where Scotland stops being cheaper | £3,549.60 | £3,549.60 | PASS |
| £30,318 — English bill at the crossover must be identical, or the crossover claim is wrong | £3,549.60 | £3,549.60 | PASS |
| Check | Expected | Computed | |
|---|---|---|---|
| £20,000 pot + £300/month at 0% for 37 years at zero growth the pot must equal the deposits, to the penny — this input used to render NaN | £153,200.00 | £153,200.00 | PASS |
| £300,000 drawdown at 0% over 300 months even draw when growth is zero | £1,000.00 | £1,000.00 | PASS |
| Check | Expected | Computed | |
|---|---|---|---|
| £250,000 at 7% over 30 years — monthly payment standard amortisation formula | £1,663.26 | £1,663.26 | PASS |
| Check | Expected | Computed | |
|---|---|---|---|
| £5,000 at 29.9% APR, minimum payments only minimums cannot cover the interest — the tool must say Never, not invent a date. It once reported "50.0 yrs"; we fixed it and test it. | Never clears | Never clears | PASS |
| Same debt with £150/month extra what actually changes the outcome | 36 months | 36 months | PASS |
| Check | Expected | Computed | |
|---|---|---|---|
| £35,000 on Plan 2 — annual repayment 9% above £28,470 | £587.70 | £587.70 | PASS |
| £45,000, Plan 2 + Postgraduate combined the two deductions stack — 15% combined marginal rate | £2,927.70 | £2,927.70 | PASS |
| Check | Expected | Computed | |
|---|---|---|---|
| £45,000 salary, £3,000 sacrificed — take-home falls by only £600 tax + £240 NI never charged: a 28% uplift before growth | £2,160.00 | £2,160.00 | PASS |
Being straight with you about the limits. These checks verify the formulas — the band logic, thresholds and edge cases — against externally known answers. They do not exercise every button in every one of the 524 tools, and they cannot know your personal tax code, benefits in kind or other income. An estimate is an estimate; your payslip and HMRC are the authoritative record.
NaN when
given a 0% rate, because the textbook formula divides by zero there. We fixed them and now
test exactly those inputs every release.← Trust Centre · All free calculators · Privacy · Your rights