Your Partnership Tax Return Paper Deadline Is 31 October: The 3 Mistakes HMRC Finds Every Time

If your business is a partnership, your paper SA800 tax return deadline is 31 October 2026. Miss it and every partner gets an automatic £100 penalty before HMRC looks at whether any tax is owed. This video covers the three common SA800 mistakes, the full penalty structure, and what nominated partners are personally responsible for. You’ll learn: ✅ What the SA800 is and who must file it ✅ Paper vs online deadlines (31 October vs 31 January) ✅ Mistake 1: getting the profit split wrong ✅ Mistake 2: missing or incorrect partner details ✅ Mistake 3: missing supplementary pages ✅ The penalty structure for every partner ✅ What the nominated partner is responsible for ✅ How each partner’s SA104 must match the SA800 ✅ What to do if you can’t meet the paper deadline Timestamps: 0:00 The 31 October deadline 0:40 What the SA800 is and who must file 1:25 Paper vs online deadlines 2:10 Mistake 1: the profit split 3:05 Mistake 2: partner details 3:55 Mistake 3: supplementary pages 4:50 The penalty structure 5:50 The nominated partner’s responsibilities 6:40 How the SA104 connects to the SA800 7:25 If you can’t meet the deadline 8:10 Recap This video is for general information only and does not constitute tax advice. Always check current guidance on GOV.UK or speak to a qualified accountant for advice specific to your situation. Selftax makes MTD-compliant software for UK sole traders and landlords. selftax.co.uk