With the 2024/25 tax year well underway, understanding how to avoid self-assessment tax penalties is crucial for maintaining tax compliance and preventing unnecessary costs.

At Hamlyns, we regularly guide our clients through the self-assessment process, ensuring they meet their obligations with complete confidence while avoiding potential penalties.

Essential Self-Assessment Deadlines to Remember

The most critical dates for your calendar are:

• 31 January 2025 for online submissions and tax payments
• 31 July 2025 for advance payments towards your bill (aka payments on account)

Missing these deadlines triggers an immediate £100 penalty, even if you owe no tax. Additional penalties accumulate over time, potentially reaching £1,600 for returns filed well past the deadline(s).

It’s vital to mark these dates and set reminders to give you a clear indication of your tax liabilities, as well as maximise your chances of obtaining a tax refund.

What Self-Assessment Tax Form Do I Need?

The primary tax return form to fill in is an SA100 form, which you can do online. If you use a paper form, this deadline has passed (31 October 2024).

You may need to complete supplementary pages if you’re informing HMRC about different types of income, including:

• SA102 – employees or company directors
• SA103F or SA103S – self-employment
• SA104F or SA104S – business partnerships
• SA105 – UK property income
• SA106 – foreign income or gains
• SA108 – capital gains
• SA109 – Dual or non-UK residents

The Importance of Effective Bookkeeping

Maintaining organised records throughout the tax year is fundamental to avoiding penalties.

We recommend:

• Creating a dedicated system for storing receipts, invoices, and important documents
• Implementing digital tools or cloud accounting software to track income and expenses
• Regularly reconciling your business transactions
• Keeping both physical and digital copies of essential documentation
• Recording all income sources, including property rental, investments, and self-employment
• Managing VAT through Making Tax Digital Solutions

Common Mistakes to Avoid

Through our experience helping clients with their self-assessment tax return forms, we’ve identified several common pitfalls:

• Forgetting to include all income sources, particularly from secondary employment or investments
• Misreporting figures due to poor record-keeping
• Overlooking allowable expenses and tax-deductible items
• Incorrectly calculating tax liabilities
• Waiting until the last minute to gather documentation

Your Self-Assessment Checklist

To ensure a smooth submission process, follow these key steps:

1. Register for self-assessment well in advance if you’re newly self-employed
2. Gather all necessary documentation, including P60s, P11Ds, and bank statements
3. Calculate your income and expenses accurately
4. Double-check all figures before submission
5. Ensure you have funds available for tax payment
6. Submit well before the deadline to allow time for resolving any issues

Seeking Professional Accounting Support

While many handle their self-assessment independently, complex tax situations may benefit from professional guidance. At Hamlyns, we offer comprehensive self-assessment services, ensuring accurate submissions and helping clients maximise legitimate tax savings while maintaining full compliance.

Remember, prevention is better than cure when it comes to tax penalties. If you’re uncertain about any aspect of your self-assessment form or need professional support, our team is here to help ensure you meet your obligations efficiently and accurately.

For more information about our self-assessment services or to discuss your tax requirements, contact our Surrey office today.