Kumberi

Kumberi is a web tool for modelling how one big life decision could affect your money in the UK. Typical questions include whether you could afford a house, what happens if one of you stops working, whether to overpay a mortgage or invest, whether you could retire at 55, or the effect of another child or a lower-paid job. It models that single choice under 2026/27 tax and pension rules.

You name the decision, add what follows from it and run a what-if comparison with two paths side by side, adding further decisions such as a job change or remortgage to the same timeline. Results begin with a plain-language verdict and let you open the assumptions, tax and cash flow behind them. The model covers income tax, National Insurance, dividends, SDLT variants, student loans and childcare, and uses ranges of market outcomes instead of a single figure.

Quick tools sit beside the main model: a mortgage calculator with remortgage paths, overpayments and shared ownership, a car cost comparison across buying, hire purchase, PCP, leasing and company car tax, and a household cash flow calculator. The site stresses that outputs are illustrations, not quotes or promises, and that it is not a bank-connected tracker.