R&D ANF Deadline: December Year-End Companies Have Until 30 June 2026

If your company has an accounting period ending 31 December 2025 and you've never claimed R&D tax relief before or haven't made a valid claim in the last three years, you have until 30 June 2026 to submit the Advance Notification Form to HMRC. After that date, your claim for this period is invalid.

The Advance Notification Form (ANF), sometimes called the claim notification form, is a mandatory pre-submission requirement introduced as part of HMRC's reformed R&D regime for accounting periods beginning on or after 1 April 2023.

It’s not required for every company, but for those in scope, the deadline is a hard one. There is no grace period and no mechanism to appeal a missed submission.

Who needs to submit the ANF?

The requirement applies if either of the following is true:

• your company has never made an R&D tax relief claim before, or
• you haven't made a valid R&D claim in the three years preceding the end of your claim notification period

If you've been claiming R&D tax relief consistently, don’t worry, you’re not affected. But for newly formed companies, businesses exploring the relief for the first time, and those returning to the scheme after a gap, the ANF is a requirement of a valid claim.

Worth noting: the three-year exemption has a specific carve-out. If your most recent R&D claim was submitted via an amended Corporation Tax return for a period beginning before 1 April 2023, and HMRC received that amendment on or after 1 April 2023, that claim does not count towards the three years.

What is the deadline for December year-end companies?

The claim notification period opens on the first day of your period of account and closes six months after it ends. For an accounting period running from 1 January 2025 to 31 December 2025, that window closes on 30 June 2026.

Company A has a December year end. Its accounting period ran from 1 January 2025 to 31 December 2025.

The company has never previously claimed R&D tax relief. To make a valid claim for this period, Company A must submit its ANF to HMRC by 30 June 2026.

If you're unsure whether the ANF applies to your company, Myriad's Advance Notification Form Checker confirms your obligation and your exact deadline in a few steps, at no cost.

Even if you’re not 100% confident in your claim, you should send HMRC your ANF. There’s no obligation to submit the full claim if you submit an ANF, but you won’t be able to make a claim if you haven’t sent one off.

What does the form require?

The ANF is a straightforward online form. You'll need:

• your company's Unique Taxpayer Reference (UTR), which must match the one on your CT600
• the name, role, and contact details of the senior internal R&D contact responsible for the claim (typically a director)
• contact details for any agents or advisers involved
• your accounting period and period of account dates
• the number of R&D projects in the period
• a high-level description of your planned R&D activities, sufficient to demonstrate the work will meet HMRC's definition of R&D

HMRC does not require detailed evidence at this stage. You won't be able to access the form once it has been submitted, so save a copy before you do.

Act before the window closes

The ANF has caught out a significant number of companies since its introduction, particularly first-time claimants and those returning after a break. The form itself is not onerous; the risk is simply not knowing the deadline exists until it has passed.

If your company has a December year end and may be in scope, check whether you need to submit an ANF now, while there is still time to act.

If you have questions about how the notification requirement applies to your circumstances, or would like guidance on your R&D claim more broadly, contact Myriad's team to discuss your specific situation.