About Casvia
Casvia makes simple, transparent financial calculators for people in the UK. Understand your money, plan with confidence.
What we do
Casvia is a small set of focused calculators covering savings, ISAs, tax, property and retirement. Every tool is designed around a few rules:
- Simple. One question at a time, plain-English results.
- Transparent. The formula and assumptions are shown on every page.
- UK-specific. Figures reference official GOV.UK and HMRC sources and state the tax year they apply to.
- Private by default. All calculations run in your browser. We have no accounts, no database and no tracking.
- Free. No sign-up, no paywall.
How we keep data up to date
UK tax rules change every year. Casvia follows a fixed review cycle so the numbers on every calculator and guide reflect the rules in force:
- Annual tax-year update. Every 6 April, when the UK tax year begins, we update all thresholds, bands and allowances for the new year.
- Budget & Autumn Statement review. After each fiscal event we re-check every figure and update anything that changes, with a note on the effective date.
- Official sources only. We cross-reference against gov.uk, gov.scot, gov.wales, HMRC, the Office for National Statistics, the Bank of England, MoneyHelper and the House of Commons Library.
- Forward-looking notes. Where a future change is already legislated (for example the Cash ISA limit from 6 April 2027), we flag it on the relevant page so you can plan ahead.
Current data version: 2026/27 tax year · Last verified September 2026. Every calculator page shows the tax year it applies to and links to the official source.
What we don't do
- We don't give personal financial, tax or investment advice.
- We don't recommend specific products, funds or providers.
- We don't collect or store anything you type into a calculator.
Who builds Casvia
Casvia is built and maintained by a software developer with 19 years of personal investing experience, based in the UK. Frustrated by finance sites that bury the maths behind sign-up walls, product pushes and opaque assumptions, Casvia was created to do one thing well: give you the number, show you how it was reached, and let you get on with it.
Every calculator is built from scratch using official UK data sources. There is no sales team, no affiliate department and no incentive to steer you towards any product. If a calculator is wrong or out of date, tell us and we fix it.
Why Casvia?
Too many finance sites bury the maths, nag you to sign up, or push products. Casvia goes the other way: open the page, type your numbers, see the answer and the formula behind it. If you want to understand how a number was reached, read the Methodology.
Casvia provides educational calculators and general information. It does not provide personal financial, tax or investment advice.