James Hartley

James Hartley founded WhatsUK to build free UK financial calculators and guides checked against official HMRC sources.

James founded WhatsUK because many free UK financial calculators were inaccurate, out of date, or hard to understand. WhatsUK launched with a small set of salary and tax tools, and has grown to cover more than 40 calculators across salary, tax, property, business, and personal finance.

James builds calculators on WhatsUK, documents the methodology behind each tool, and checks rates against official HMRC publications before each tax year begins on 6 April. Guides cover topics such as personal allowance tapering, corporation tax marginal relief, IR35 status assessment, CIS deduction rates, and stamp duty first-time buyer relief in plain English.

He also authors articles on the WhatsUK blog, translating changes to UK tax rates and legislation into guides that anyone can follow. Articles are checked against official HMRC sources before publication.