R&D tax credits allow UK limited companies to reduce Corporation Tax or receive a cash repayment for developing new or improved products, software or processes where scientific or technological uncertainty existed. Claims must now follow strict HMRC compliance rules, including advance notification, a detailed technical narrative, an Additional Information Form and correct reporting on the CT600 tax return.

In this comprehensive guide, we cover everything you need to know about limited company expenses in the UK—what you can claim, what you can’t, how to record it, and the golden rules that make it all legitimate.