On 1 January, the UK doesn’t just start a new calendar year. It starts a tax sprint.
For some, January is the month you finally “close the file” on the 2024/25 tax year (ended 5 April 2025). For others, it’s a routine cadence: payroll, CIS, VAT. For limited companies, January can also be the month where an old accounting period catches up with a filing deadline.
The trick is simple: know which January deadlines apply to you, and build a short checklist you can actually follow.
Part 1 — Individuals (Self Assessment: where January really bites)
The big date: 31 January 2026
If you file Self Assessment online for 2024/25, HMRC must receive:
- your online tax return, and
- any tax due
by 11:59pm on 31 January 2026.
This is not just a “paperwork” deadline. It is also a cash deadline.
What typically becomes payable on 31 January?
Depending on your circumstances, 31 January 2026 may include:
- Balancing payment for 2024/25 (what’s still due after tax already collected)
- First payment on account for 2025/26 (an advance payment towards the next year)
HMRC’s payments on account are generally due in two instalments: 31 January and 31 July.
Miss the deadline? Penalties escalate fast
HMRC’s late filing penalties for Self Assessment start with an automatic £100, then escalate with daily penalties and further charges at 6 and 12 months.
Late payment penalties can also apply (5% surcharges at 30 days, 6 months and 12 months), plus interest.
A common January trap: UK property disposals
If you sold UK residential property and there is CGT to pay, the reporting/payment deadline can be 60 days from completion (for completions on/after 27 October 2021).
That’s not a “January deadline” in the calendar sense — but it often lands in January when completions happen in November/December.
Part 2 — Businesses (January is compliance month)
Employers: PAYE / NIC payment deadlines (January 2026)
If you run payroll, HMRC payment is due:
- by the 22nd of the next tax month if you pay electronically, or
- by the 19th if paying by cheque through the post.
So, for many employers, 22 January 2026 is the key “PAYE payment day” (subject to your payroll period).
Part 3 — Construction businesses (CIS): two January dates that matter
CIS monthly returns: by 19 January 2026
CIS contractors must send monthly returns to HMRC by the 19th of every month following the last tax month.
That means 19 January 2026 is a live filing deadline for the relevant CIS month.
Paying CIS deductions (often paid with PAYE)
CIS deductions are paid to HMRC monthly by the 22nd (or 19th if paying by post).
Part 4 — VAT-registered businesses: January can be a VAT deadline month
VAT deadlines are driven by your VAT stagger and accounting period end date. The general rule is:
- the VAT Return and payment deadline is usually one calendar month + 7 days after the end of the VAT accounting period.
Practical January example
If your VAT quarter ended 30 November 2025, the normal deadline is 7 January 2026 (1 month + 7 days).
Part 5 — Limited companies: January deadlines depend on your year-end
Corporation Tax payment: can be 1 January 2026 for March year-ends
Corporation Tax is normally payable 9 months and 1 day after the end of the accounting period (unless you’re large enough to be in instalments).
So a company with a 31 March 2025 year-end would usually have a Corporation Tax payment deadline of 1 January 2026.
Company Tax Return (CT600): can fall due in January 2026
The deadline for a Company Tax Return is 12 months after the end of the accounting period.
So a company with an accounting period ending 31 January 2025 would typically face a 31 January 2026 CT600 filing deadline.
Companies House accounts: many April year-ends land on 31 January
Private companies generally have 9 months to file accounts after the accounting reference period end.
If your accounting reference date is 30 April 2025, nine months later is 31 January 2026 — a very common “January accounts deadline” scenario.
January 2026: quick checklist by date
By 7 January 2026
- VAT Return + payment for VAT periods ending 30 November 2025 (typical example under the “1 month + 7 days” rule).
By 19 January 2026
- CIS monthly return (CIS contractors).
- PAYE/CIS payment if paying by post/cheque (where applicable).
By 22 January 2026
- PAYE/NIC (and often CIS deductions) payment if paying electronically.
By 31 January 2026
- Online Self Assessment filing and payment for 2024/25.
- First payment on account for 2025/26 (where applicable).
- Some CT600 deadlines (12 months after period end).
- Some Companies House accounts deadlines (common for 30 April year-ends).
Need a January “tax health check”?
If you’re unsure which deadlines apply (especially where you have mixed income, property, director/shareholder positions, VAT, or cross-border elements), we can map it quickly and prioritise what must be done first.
Contact: angelo@vectigalistax.co.uk