UKCalc analysis
Original analysis derived from UKCalc's verified statutory data and its own calculation logic. These pages answer questions the official sources set the rules for but do not work out for you.
Every page separates statutory facts from UKCalc's assumptions and from UKCalc's derived analysis, and links the primary source for each figure. The underlying statutory values are published on UK rates and thresholds 2026/27.
The UK effective marginal tax rate map, 2026/27
UKCalc derives a 69.5% combined marginal rate — Income Tax plus employee NI — between £116,760 and £125,140 under 2026/27 rules.
The first-time buyer stamp duty cliff at £500,000
A first-time buyer paying £500,000 owes £10,000 in SDLT. At £500,001 relief is lost entirely and the bill is £15,000 — £5,000 more for £1 more on the price.
Mortgage affordability and rate sensitivity
How much a 1 percentage point rate move, a bigger deposit or a longer term actually changes a UK mortgage. On a £270,000 loan over 25 years, 1pp is about £153 a month.