Tax Diary: January to February 2026 Deadlines That May Still Matter

This tax diary highlights key UK tax deadlines that fall between January and February 2026. It is intended for taxpayers reviewing whether all obligations following the January deadline were dealt with correctly.

Although the main Self Assessment deadline has passed, there can still be filing, payment, and compliance issues linked to this period that remain relevant.

Key Tax and Payroll Deadlines for January and February 2026

• 1 January 2026 – Due date for Corporation Tax due for the year ended 31 March 2025
• 19 January 2026 – PAYE and NIC deductions due for month ended 5 January 2026. (If you pay your tax electronically the due date is 22 January 2026).
• 19 January 2026 – Filing deadline for the CIS300 monthly return for the month ended 5 January 2026.
• 19 January 2026 – CIS tax deducted for the month ended 5 January 2026 is payable by today.
• 31 January 2026 – Last day to file 2024-25 self-assessment tax returns online.
• 31 January 2026 – Balance of self-assessment tax owing for 2024-25 due to be settled on or before today unless you have elected to extend this deadline by formal agreement with HMRC. Also due is any first payment on account for 2025-26.
• 1 February 2026 – Due date for Corporation Tax payable for the year ended 30 April 2025.
• 19 February 2026 – PAYE and NIC deductions due for month ended 5 February 2026. (If you pay your tax electronically the due date is 22 February 2026)
• 19 February 2026 – Filing deadline for the CIS300 monthly return for the month ended 5 February 2026.
• 19 February 2026 – CIS tax deducted for the month ended 5 February 2026 is payable by today.

Why Post-January Deadlines Still Matter

Missing a January deadline does not end the obligation. Where returns or payments were late, HMRC continues to treat them as outstanding until they are resolved.

February is often when taxpayers begin to see the consequences of missed January obligations, including interest charges or follow-up correspondence, sometimes highlighted during a later review by a tax specialist in London or through HMRC checks.

Common Obligations Around January and February

Deadlines and follow-up actions during this period often relate to:

• Late Self Assessment tax returns
• Unpaid tax balances following the January deadline
• Payments on account where applicable
• VAT return submissions and payments
• PAYE and National Insurance reporting and payments

Which obligations applied will depend on your circumstances, such as whether you were required to file a Self Assessment return or make payments on account.

What Happens If January Deadlines Were Missed?

Missing the January filing deadline usually triggers an automatic late filing penalty. Interest is also charged on any unpaid tax from the original due date.

If delays continue, further penalties may apply. Even if no immediate action was taken by HMRC, unresolved issues can still be pursued later through statements, reminders, or compliance checks.

Why It Is Worth Reviewing This Period Now

Some taxpayers assume that once January has passed, missed deadlines are no longer relevant. In practice, issues linked to January often surface in February and beyond.

Reviewing whether all January and February 2026 obligations were met can help prevent problems escalating later in the tax year.

HMRC Guidance on Late Filing and Payment

HMRC provides guidance on late filing, late payment, penalties, and interest on
GOV.UK.

Did You Miss Any January or February 2026 Deadlines?

Whether any action is required now will depend on which obligations applied to you at the time and whether they were dealt with correctly. For individuals and businesses in Fulham Broadway and nearby areas such as Eel Brook Common and Fulham Palace Road, CIGMA Accounting can review your position and confirm whether anything remains outstanding or needs to be addressed.