Tax Week Calendar 2026/27: Key Dates for Self Assessments

As the new tax year begins, it's the ideal time to get ahead of your Self Assessment responsibilities. Whether you're managing your own accounts or juggling multiple income streams, understanding the key deadlines can help you stay organised, avoid penalties and keep your finances running smoothly.

In this guide, we outline the key dates for the 2026/27 tax year, along with practical context to help you plan ahead. We'll also reference the tax week calendar 2025/26, as many of your current obligations will relate to that period.

The April Changeover: Closing One Year, Starting the Next

The transition between tax years is a valuable window for reviewing your finances and setting yourself up for the months ahead. Here's what you should be aware of this month:

5 April 2026: End of the 2025/26 Tax Year
This marks the final day to make use of any available allowances or reliefs for the 2025/26 tax year. Taking time to evaluate your financial position now, including income, expenses, and eligible claims, can help ensure you're not paying more tax than necessary.

6 April 2026: Start of the 2026/27 Tax Year
The new tax year begins. It's a good opportunity to reset your approach, check your tax code, and ensure your record-keeping is accurate from the outset. With Making Tax Digital for Income Tax starting from April 2026, keeping well-organised digital records will be more important than ever.

Key Self Assessment Deadlines for 2026/27

First, we'll look at the traditional Self Assessment deadlines, which remain in place. We'll then explore what the introduction of Making Tax Digital (MTD) for Income Tax in April 2026 means for some taxpayers.

30 April 2026: Final Deadline for Late 2024/25 Returns
If your 2024/25 tax return is still outstanding, this is a critical and potentially costly deadline. Missing it results in an initial £100 penalty, with additional charges applied over time, including daily penalties after three months, followed by further fines at six and twelve months.

31 July 2026: Second Payment on Account (2025/26)
Your second payment on account for the 2025/26 tax year is due, as reflected in the tax week calendar 2025/26.

5 October 2026: Register for Self Assessment
If you've started self-employment or received untaxed income during the 2025/26 tax year, you must register by this date.

31 October 2026: Paper Filing Deadline
Final deadline for submitting paper tax returns.

30 December 2026: PAYE Collection Deadline
Submit your return by this date if you want tax (under £3,000) collected via your PAYE code.

31 January 2027: Final Submission and Payment Deadline
You must:

Submit your online tax return for 2025/26
Pay any outstanding tax
Make your first payment on account for 2026/27

31 July 2027: Second Payment on Account (2026/27)
Your next advance payment is due.

Making Tax Digital: What It Means for Your Tax Calendar

From April 2026, Making Tax Digital (MTD) for Income Tax comes into effect for individuals earning over £50,000 from self-employment or property.

This represents a significant shift in how tax is reported. Instead of submitting one annual return, you will need to:

Keep digital records using compatible software
Submit quarterly updates to HMRC
Complete an End of Period Statement (EOPS)
Submit a final declaration to confirm your overall tax position

For those earning over £30,000, these requirements are expected to apply from April 2027, so it's worth preparing early.

If you fall within the MTD threshold, the new quarterly deadlines that you need to be aware of are:

7 August 2026: First quarterly update (covering April–June)
7 November 2026: Second quarterly update
7 February 2027: Third quarterly update
7 May 2027: Fourth quarterly update

After the end of the tax year:

31 January 2028: Final declaration and tax payment deadline

These updates are based on cumulative income and expenses recorded digitally throughout the year.

Keeping Your Tax Year on Track

Approaching your Self Assessment deadlines with a clear plan can make the process far more manageable. Rather than reacting to deadlines as they arise, mapping them out in advance allows you to stay organised, manage cash flow, and reduce the risk of penalties.

With the right preparation, the tax calendar becomes a helpful tool rather than a source of stress.

At Keith Graham, we work closely with individuals and businesses to provide clear, practical support with Self Assessment and tax planning. If you'd like guidance throughout the year, our experienced team is here to help.
Please get in touch today to learn more about our tax planning services.