Deadlines and Penalties

• Avoid January bottlenecks. HMRC systems and helplines are busiest in January. Filing earlier means faster responses and fewer hiccups.
• See your bill sooner. Knowing your bill months in advance gives you time to budget or set up a Time to Pay plan with HMRC if needed.
• Fix missing information calmly. If you’re waiting on a P11D, bank interest figure, or CGT details, you can file once you have them, no last-minute scramble.
• Reduce penalty risk. On-time filing avoids automatic penalties and keeps late-payment charges to a minimum if cash is tight. HMRC’s late-payment penalty and interest rules are strict, so the earlier you act, the cheaper it is.

• Automatic penalties apply immediately after the deadline—even if no tax is due. Further penalties accrue the longer you delay, and late-payment penalties are charged at 30 days, 6 months and 12 months after the payment due date, with interest running until the bill is cleared. Filing first, even if you can’t pay yet, limits the damage.
• Interest changes over time. HMRC updates late-payment and repayment interest in line with Bank of England movements. Check the current rate before you decide to delay payment.

Use these dates as your high-level checklist for the 2024/25 tax year (income from 6 April 2024 to 5 April 2025):

• Register for Self Assessment (if it’s your first time): by 5 October 2025.
• File a paper return (if you’re not filing online): by 31 October 2025.
• File online (SA100 via software like Ftax): by 31 January 2026 (11:59pm).
• Pay your bill (balancing payment and, if applicable, your first Payment on Account): by 31 January 2026.
• Second Payment on Account (if applicable): by 31 July 2026.

Tip: If HMRC sends you a notice to file after 5 October, your filing deadline may be 3 months from the date of that notice, but the 31 January payment deadline still applies.

Getting your records in order now makes filing faster and more accurate:

• IDs: National Insurance number; Government Gateway user ID/password (for HMRC authorisation).
• Income: P60/P45, P11D, employment benefits, bank interest, dividends, pensions, state benefits.
• Self-employment (if relevant): income and allowable expenses (software, equipment, use of home, mileage); we’ll activate SA103 automatically.
• Property (landlords): rental statements, agent fees, repairs, mortgage interest restriction notes; we’ll add SA105 for you.
• Capital gains: dates/costs/proceeds for disposals of shares, crypto, or property; we’ll include SA108 where needed.
• Foreign income: overseas interest/dividends/rent; we’ll add SA106 when applicable.
• Reliefs & adjustments: pension contributions, Gift Aid, student loan, marriage allowance, trading/property allowances.

Ftax turns on only the sections you need, validates entries to catch common errors, and produces a calculation you can trust before submission to HMRC.