Why plain English
Most budget and tax templates are American, or written by people who assume you already know what a Class 4 threshold is. Ours are built around UK rules, and every rate sits on a Settings tab next to the gov.uk page it came from. If you want to check a figure, you can. If a figure changes, you can change it.
How they're made and checked
Each spreadsheet is built in Excel with ordinary formulas: no macros, no add-ins, nothing to install. Before release it goes through three passes: a formula audit, a buyer walkthrough where the results are checked against hand calculations from gov.uk figures, and an adversarial pass that tries to break it with odd inputs. The Sole Trader Bookkeeping and Director Salary vs Dividend sheets carry both the 2025/26 and 2026/27 rates and pick the right ones for the year you choose.
What they are not
They are record-keeping and planning tools, not tax advice, and PlainSums is not affiliated with HM Revenue and Customs. If your situation is unusual, talk to an accountant. If you find a mistake in a spreadsheet or a guide, please tell us: we fix it, and anyone who bought the file can message us on Etsy with their order number for the new version, free.
Contact
Email hello@plainsums.co.uk. We answer questions about the spreadsheets, but we can't answer questions about your own tax.