When Is the Self-Assessment Deadline? Key Dates for 2024/25

All the important Self-Assessment deadlines you need to know, including paper and online filing dates.

Why this matters for digital businesses

Self Assessment deadlines matter because HMRC penalties are triggered by dates, not by how complicated your return was. Digital business owners often have several income streams, so the safest approach is to treat the filing date as the final checkpoint rather than the start of the work. Amazon payouts, creator platform income, bank interest, dividends, pension contributions, and payment-on-account figures all need to be reviewed before the return is submitted.

Key checks before you act

• Confirm whether you need to file online, on paper, or through an accountant acting as your agent.
• Reconcile marketplace, platform, and bank income before calculating your taxable profit.
• Check payments on account as well as the balancing payment due for the tax year.
• Keep evidence for expenses, mileage, home office costs, subscriptions, and professional fees.

Common mistakes to avoid

• Waiting until January to collect platform statements, which leaves little time to fix missing data.
• Assuming tax is only due on cash withdrawn from the business rather than taxable profit.
• Forgetting that late payment interest can apply even when the return itself was filed.

Next steps

1. Create a deadline calendar for registration, filing, payment, and evidence collection.
2. Export income and fee reports from each sales or creator platform before year end.
3. Ask for a review if you have mixed employment, self-employment, dividends, or overseas platform income.

Questions digital businesses ask