SA800 is the Partnership Tax Return a UK partnership sends HMRC each year to report the partnership's income and how profits are shared. For the 2025 to 2026 tax year, a paper return is due by 31 October 2026 and an online return by 31 January 2027. If it's late, HMRC charges a £100 penalty to every person who was a partner during the period, not just once.
Everything below comes from HMRC's SA800 2026 return and the SA850 Partnership Tax Return Guide for the tax year 6 April 2025 to 5 April 2026, as of October 2026.
Deadlines for the 2025 to 2026 return
| Date | What's due |
|---|---|
| April 2026 | The return is issued: check which supplementary pages you need |
| 31 October 2026 | Paper Partnership Tax Return, and partners' own paper returns |
| 31 January 2027 | Online Partnership Tax Return, partners' online returns, balance of tax owed and the first payment on account for 2026 to 2027 |
You may have longer if HMRC gave notice to file after 31 July 2026, or if the partnership includes a company as a partner. HMRC's guide covers both cases.
Late filing penalties are charged per partner
This is the point that makes SA800 expensive to miss. Penalties aren't charged to the partnership once; they're charged to each partner who was a member during the return period.
| How late | Penalty for each partner |
|---|---|
| Missed deadline | £100 |
| Over 3 months late | £10 a day for up to 90 days (£900) |
| Over 6 months late | A further £300 |
| Over 12 months late | A further £300 |
So a four-partner firm that's 6 months late faces four sets of those penalties, as of October 2026. Add up the first three rows of the table for one partner, then multiply by every partner on the return, and the cost of a forgotten SA800 becomes very clear, before any penalties on the partners' own returns. And if the partnership return is late and that makes the partners' personal returns late, their automatic penalties apply too.
What's in the return
Every partnership gets the first 8 pages, covering trade and professional income and interest from banks, building societies or deposit takers. Supplementary pages cover less common income and disposals of chargeable assets. The partner completing the return is responsible for choosing the right supplementary pages and sending them on time.
The Partnership Statement shows how profits or losses are shared. The short statement caters for up to 3 partners; the full one caters for up to 6. If you have more partners, photocopy page 7 or download extra pages. Partners then use a copy of the statement to fill in the Partnership pages of their own returns, so get it to them before their deadlines.
Who signs it and what HMRC checks
The return must be filled in and signed by the partner nominated by the other partners, or by HMRC, or the partner named on the front of the form. All the partners are responsible for its accuracy, not only the one who signs. Don't send the financial records with the return, but keep them safe: HMRC has 12 months after it receives the return to check it, and it may ask for the records and compare the figures with details from other sources, such as your bank.
A few form-filling rules from the guide save rejections: use numbers only, don't include pence, round income down and tax credits and deductions up, and never write 'per attached' or 'to follow' in a box. Don't hold the return back because some information is missing either. If, despite your best efforts, you can't give final figures, the guide explains when HMRC accepts provisional ones: tick box 10.1 on page 8, explain why in box 3.116 and give a date for the final figures. The common case is a new business whose first accounting period ends within 3 months of the filing date, or after it.
Filing online needs software
Here's the catch for small partnerships: to file the Partnership Tax Return online, you register with HMRC's online service and then buy commercial software. You can file online even if HMRC sent you a paper return, and an online return received by 31 January 2027 avoids the automatic penalty.
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Filing SA800, step by step
- Have the partnership's Unique Taxpayer Reference and each partner's reference to hand.
- Gather the partnership's records for the accounting period.
- Complete the first 8 pages and any supplementary pages that apply.
- Complete the Partnership Statement, short or full, allocating profit or loss to each partner.
- File by 31 October 2026 on paper or 31 January 2027 online, using commercial software for online filing.
- Give every partner a copy of the statement for their own SA100 return.
Need your reference number? See how to find a UTR number.
If partners disagree with their share
A partner who doesn't agree with the profit or loss allocated to them has the right to refer it to the Tribunal Service. HMRC recommends trying to settle it between yourselves first. If a partnership is itself a member of another partnership, or has a partnership as a member, the guide has extra rules on the statements you need.
The verdict
Treat the SA800 as the partnership's job, not each partner's: one person files it, but everyone pays if it's late. Aim for the 31 October paper date or file online well before 31 January, budget for the software and send each partner their statement early. For the wider picture on fines, see late tax return penalties.
Frequently asked questions
When is the SA800 due?
For 2025 to 2026, paper returns are due by 31 October 2026 and online returns by 31 January 2027.
What is the penalty for a late Partnership Tax Return?
Each partner who was a member during the period is charged £100, then £10 a day after 3 months for up to 90 days, and £300 at 6 and again at 12 months.
Can I file the SA800 online for free?
To file online, you register with HMRC's online service and then buy commercial software.
How many partners does the short Partnership Statement cover?
The short Partnership Statement caters for up to 3 partners and the full one for up to 6.
What can a partner do if they disagree with their profit share?
They have the right to refer the allocation to the Tribunal Service. HMRC recommends trying to resolve it with them first.
