UK Self Assessment Guide 2026/27

Why this one

The tax return is not difficult. It is unfamiliar, which is a different problem and a much easier one to fix. This guide walks the whole thing from registering to paying, explains what each section is asking for in ordinary words, and tells you which parts you can safely ignore. It covers the registration sequence and how long the post actually takes, every tailoring question and what turning it on does, the self-employment pages box by box, how a job alongside self-employment is taxed with the arithmetic written out, and a full chapter on payments on account — the reason a first January bill is half as large again as the tax you were expecting. It ends with a month-by-month calendar and a checklist you can print.

What you get

• A guide in 20 chapters, as a PDF
• Do you actually need to file one?
• Registering, and the deadline nobody knows about
• What you need in front of you before you start
• Tailor your return: the questions that decide what you see
• The return, section by section, in the order it appears
• The self-employment pages in detail
• If you have a job as well
• Payments on account: the bill that is 150% of the tax
• Reducing your payments on account, and when not to
• Budget payment plans and Time to Pay
• How to pay, and how long each way takes
• Having it collected through your tax code
• Changing a return after you have filed it
• If you are late
• What a reasonable excuse actually is
• Records: what to keep, and for how long
• Edge cases that come up in a first return
• Mistakes worth avoiding, and what each one costs
• The Self Assessment year, month by month
• The one-page checklist

Need more than one? This is also in the UK Self Employed Complete Tax Bundle 2026/27 (£30.99) — the same files at a lower price than buying them one by one.

Questions