• UK rules
  • 2026/27 tax year
  • Excel + Google Sheets

Honest sums for UK money decisions

HonestSums makes plain spreadsheets for the money decisions most of us face a few times in life: taking a new job, overpaying a mortgage, buying a rental, paying for childcare, keeping a side hustle straight with HMRC. Each one follows the published GOV.UK rules, says when those rules were checked, and shows its working.

The three calculators below are free, quick versions of the spreadsheets. They run in your browser, so nothing you type is sent anywhere. When you want the full picture, with what-ifs and a Checks tab that proves the figures against worked examples, the spreadsheets are a small one-off download that works in Excel and Google Sheets.

Free calculators

Take-home pay 2026/27

Your salary after income tax, National Insurance, student loan and pension salary sacrifice, a year and a month. Scotland included.

Work out my take-home pay

Mortgage overpayment

How much interest overpaying saves you, how many months come off, and your new mortgage-free date.

See what overpaying saves

Stamp duty (England and NI)

Stamp Duty Land Tax at today's rates, with first-time buyer relief and the 5% surcharge on second homes and buy-to-let.

Work out my stamp duty

Yellow cells are yours; everything else is done for you. Every sheet has a Checks tab, works in Excel 2010 or later and Google Sheets, and the tax-year sheets are updated every April.

UK Take-Home Pay and Salary Sacrifice Calculator 2026/27

See what actually lands in your bank account each month, and what salary sacrifice really costs you.

See this spreadsheet: take-home pay

UK Buy-to-Let Deal Analyser 2026/27

Cash needed, monthly cash flow, yield, the lender's stress test, and tax in your own name or a limited company.

See this spreadsheet: buy-to-let

UK Childcare Cost Calculator (England)

What nursery or a childminder really costs each month once free hours, Tax-Free Childcare or Universal Credit come off.

See this spreadsheet: childcare

UK Redundancy Pay, Notice and Bridging Budget Calculator 2026/27

What your redundancy is really worth after tax, and how long the money lasts until your next job pays.

See this spreadsheet: redundancy

UK Inheritance Tax Estimator

What Inheritance Tax your estate would pay today, and what changes with a charity gift, the family home or a gift now.

See this spreadsheet: inheritance tax

UK Company Car vs Car Allowance Calculator 2026/27

Company car, cash allowance or salary-sacrifice electric car: which leaves you better off each month.

See this spreadsheet: company car

UK Student Loan Repayment and Overpayment Planner

What your student loan will really cost, when it ends, and whether overpaying saves you anything at all.

See this spreadsheet: student loan

UK Pension Contribution and Tax Relief Calculator 2026/27

What paying into your pension really costs from your take-home pay, and how much lands in your pot.

See this spreadsheet: pension tax relief

Prefer to buy direct? The same sheets are in the HonestSums Payhip store, or browse the whole Etsy shop.