I built a free UK tax calculator that shows exactly how much pension salary sacrifice saves you

I got fed up trying to model different salary sacrifice scenarios in spreadsheets, especially around the £100k personal allowance taper where the effective tax rate hits 60%.

So I built a free web app that lets you plug in your income and instantly see your tax breakdown for 2024-27, then use the pension optimiser to see exactly how much you'd save by increasing contributions via salary sacrifice, including the NI savings most calculators miss.

It also covers:

• Calculates income tax, NI, student loan repayments, and dividend tax across multiple income sources (PAYE, self-employment, rental, dividends, savings interest)
• Capital gains tax (useful for tracking ISA overflow / GIA disposals)
• What-if calculator for modelling different scenarios
• Multi-profile support so you can compare e.g. current year vs next year or multiple people in the household.
• Ltd vs sole trader comparison

It's a PWA so you can install it on your phone/desktop, runs entirely in your browser (nothing stored on a server), and it's completely free.

Link: https://uk-budget-tracker.com

To get started just head to the 'Help' page for an overview and I also think it works best on desktop!

Would love any feedback or comments! Let me know if you have any questions!