Every practice knows the Self Assessment busy season is coming. This year it has company. Online returns for the 2025 to 2026 tax year are due by 31 January 2027, and clients already in Making Tax Digital for Income Tax have a quarterly update due one week later, on 7 February.
This guide gives you a simple plan for the next 11 weeks. It shows how to sort your client list, set weekly targets, fit the February update around the January peak and decide early whether you need extra help. We provide outsourcing for accounting practices, and our team is led by an ACCA member, so we have a commercial interest in this topic. The plan works whichever route you choose.
The short answer
- Sort every Self Assessment client into one of four groups this week, based on what you have received.
- Work back from 31 January and set a weekly target for returns ready for review.
- Book review time and the 7 February updates now, before January fills the diary.
The dates that shape the next 11 weeks
These are the dates your plan has to work around. Check them against GOV.UK’s Self Assessment deadlines and HMRC’s guidance on quarterly updates.
| Date | What is due |
|---|---|
| 30 December 2026 | Online return, if an eligible client wants tax under £3,000 collected through their tax code |
| 31 January 2027 | Online return for 2025 to 2026, the balancing payment and the first payment on account for 2026 to 2027 |
| 7 February 2027 | Third quarterly update for Making Tax Digital clients, covering 6 April 2026 to 5 January 2027 |
A late return brings a £100 penalty straight away, with more if it stays late, as set out on GOV.UK’s penalties page. HMRC says it will not apply penalty points for late quarterly updates in the 2026 to 2027 tax year. That is not a reason to leave them. The updates still have to be sent before the client can file their tax return through software.
Sort your clients into four groups before the busy season
Do this once, this week. Use whatever you have, such as a spreadsheet or your practice software.
- Ready. Records are in and complete. These go into preparation now.
- Partly in. Some records are missing. Send one list of everything still needed, with a date.
- Not started. Nothing received. Send a firm request and a date by which you need the records.
- At risk. Late registrations, complex cases or clients who are always late. Flag these for a partner decision.
The aim is to move as many clients as possible from groups 2 and 3 into group 1 before Christmas. Every return prepared in December is one fewer in the last two weeks of January.
Work back from 31 January
A deadline on its own does not tell you what to do this week. A weekly target does.
- Count the returns still to file.
- Count the working weeks left before your own cut-off. Set that cut-off a week or so before 31 January, so there is room for late changes and client approval.
- Divide the first number by the second. That is the number of returns you need ready for review each week.
- Check it against your review hours. If one person reviews everything, their hours set the real limit.
This is a planning sum, not a forecast. Client records will arrive in an uneven way, so check progress each Friday and move the target if you need to.
Fit 7 February around the January peak
For Making Tax Digital clients, the third quarterly update falls in the week after the busiest week of the year. A few steps now make it easier:
- list every client who is signed up, and which software they use, such as Xero, QuickBooks, Sage, FreeAgent or KashFlow
- ask those clients to keep their records up to date through December, so the update is mostly a check
- book the time for these updates in your diary for the first week of February now
- where a client is also filing a return in January, check the year so far while you have their records open
Decide on extra help by mid-December
If your weekly target is more than your team can prepare and review, you have three choices. You can take on fewer new clients, bring in temporary staff, or outsource some preparation. Each needs time to set up. A decision made in the second week of January is usually too late. If you’re unsure, a pilot on a few returns with complete records in late November or December will tell you more than a plan will.
If you are thinking about outsourcing, the same rules apply as for any handover. Keep advice, client contact and final sign-off with your team. Hand over preparation of returns where the records are complete, because those are the easiest to check. Our guide on what to outsource first explains how to choose and how to run a small pilot.
Want a second pair of hands this January? Book a free call with our team. Bring your client count and your weekly target, and we’ll work out together which returns could be prepared for your review and when a handover would need to start. Your practice keeps the client relationship and sign-off. No obligation. Book a call about your January workload.
Check progress every Friday
Track four numbers each week until 31 January:
- returns filed
- returns ready for review
- clients still in groups 3 and 4
- returns waiting for client approval
If returns waiting for review keep growing, the problem is review time, not preparation. Move review hours before you add more preparation.
What to do after 31 January
Write down what went wrong while it is fresh. Which clients were late, where work waited and what you would start earlier next year. That note is the first page of next year’s plan. If your Friday numbers show review or preparation falling behind, read about our Self Assessment outsourcing service before the January peak.
FAQ
When is the Self Assessment deadline for the 2025 to 2026 tax year?
Online returns are due by 31 January 2027. The balancing payment and the first payment on account for 2026 to 2027 are due on the same day.
When is the third Making Tax Digital quarterly update due?
By 7 February 2027, for the period from 6 April 2026 to 5 January 2027. This applies to both standard and calendar update periods.
Are there penalties for late quarterly updates this year?
HMRC says it will not apply penalty points for late quarterly updates in the 2026 to 2027 tax year. Penalty points still apply to late tax returns.
When should a practice decide on outsourcing for January?
Ideally by mid-December. A handover needs time to settle, and starting it in January leaves little room to fix problems.
This article is general information for accounting practices, not professional advice. Dates and rules were checked against GOV.UK on 11 November 2026.
