Self Assessment has a rhythm. Miss it and you risk penalties, interest and a scramble for paperwork you could have gathered steadily through the year. For owner-managers across Mid-Ulster, the calendar is straightforward once you know which deadlines apply to you, and what HMRC expects in the months before January.
The dates that matter
For the 2026/27 tax year cycle, the dates most clients ask about are 31 January for online filing and the balancing payment (plus the first payment on account where due), 31 July for the second payment on account, and 5 October if you need to register for Self Assessment for the first time.
Not everyone pays on account. It depends on how much tax you owed previously and whether HMRC has issued notices. We check that with you as part of our Personal Tax work rather than assuming the same pattern as last year.
If you want a live countdown to the next filing point, use the Self Assessment Deadline tool on our Tools page. It is a useful reminder, not a substitute for knowing which notices apply to you.
What to gather early
Start a shared folder for employment income (P60 or P45), dividend vouchers, bank interest, rental schedules, self-employment income and expenses, pension contributions and Gift Aid certificates. The earlier those sit in one place, the less January feels like archaeology.
If you already use Xero or another cloud system, share access so we can reconcile to HMRC records before the rush. Mid-Ulster landlords with several properties should keep rent and expense streams separate. That habit saves hours when Making Tax Digital for Income Tax arrives.
Directors who extract both salary and dividends should also keep an eye on how those figures land in Self Assessment. Our note on Salary vs Dividend in 2026/27 covers the extraction side of the same picture.
Payments on account, without the jargon
Payments on account are advance payments towards next year's bill, usually two equal amounts based on the previous year's liability. They catch people out when profits fall, because HMRC still expects the same pattern unless you reduce them properly.
If trading is softer this year, speak to us before July. Reducing payments on account is legitimate when the estimate is realistic. Leaving it until a cash crunch in January is how interest and stress pile up.
How Gortreagh helps
We diary your deadlines, send clear checklists, prepare the return and talk through the payment figure before anything is submitted. That is the core of our Compliance and Personal Tax support for Mid-Ulster clients.
If you are switching accountants mid-year, professional clearance and a tidy handover of prior returns matter as much as the next filing date. We handle that as standard when you get in touch.
"A short conversation now is cheaper than a late filing later."
Eoín Brannigan, Gortreagh Consulting