R&D Tax Claim Notification Form: Are You Compliant?

The claim notification form is a new administrative requirement introduced as part of HMRC's reformed R&D tax relief regime. Miss the deadline, and your claim is invalid, regardless of how well-documented your R&D activities are.

This post explains who needs to submit the form, how to work out your deadline, and what information you'll need to provide.

What is the claim notification form?

The claim notification form (also referred to as the Advance Notification Form, or ANF) is an online form submitted to HMRC to confirm that your company intends to make a claim for R&D tax relief or expenditure credit. It applies to accounting periods beginning on or after 1 April 2023.

Importantly, it’s only a requirement for companies claiming for the first time, or for the first time after a break.

It can be submitted by a representative of the company or an agent acting on the company's behalf, like an accountant or an R&D tax credit adviser. The form asks for basic details about your company, your R&D projects (high-level information only) and your claim dates, and any advisers involved. It does not replace the actual R&D tax credit claim process.

Myriad has developed the UK's first Advance Notification Form Checker so you can confirm whether you need to submit an ANF at all. It's free to use and will also give you your claim notification deadline, if you have one.

Do you need to submit a claim notification form?

Not every company claiming R&D tax relief is required to submit one. Whether you need to depends on two questions:

1. Have you claimed R&D tax relief before?

If this is your first claim ever, you must submit a claim notification form.

Even if a company in your group has made an R&D tax credit claim before, or a key member of your team, you will still need to submit a form if the company has never included an R&D tax credit claim on its Company Tax return before.

2. When did you last make an R&D claim?

If you've claimed before, you only need to submit a claim notification form if your last valid claim was made more than 3 years before the last date of your claim notification period (see below for how to work this out).

Worth noting: if you've previously filed a Corporation Tax return on paper, submitting an ANF is advisable to prevent delays when HMRC processes your claim.

Amended Corporation Tax returns

There's one specific exception that's worth understanding. A previous R&D claim doesn't count towards the 3-year exemption if all of the following apply:

• It relates to an accounting period beginning before 1 April 2023

• It was submitted via an amended Corporation Tax return (CT600)
• HMRC received that amendment on or after 1 April 2023

If your situation matches these criteria, that earlier claim is disregarded when calculating whether you've claimed within the past 3 years.

You may need to submit an ANF even if you believed you were exempt. If you're uncertain, use Myriad's ANF Checker or speak to an adviser before assuming you're covered.

When is the deadline to submit the claim notification form?

Your claim notification period runs from the first day of your period of account to 6 months after the period of account ends. You can submit the form at any point within that window — but you must do so before the last date.

Standard 12-month periods of account

For most companies, the accounting period and period of account are the same 12-month window. In this case, your claim notification period is effectively 18 months from the first day of the accounting period.

Here's what that looks like in practice:

A company's accounting period and period of account both run from 1 April 2025 to 31 March 2026. The claim notification window opens on 1 April 2025 and closes on 30 September 2026 — 6 months after the period of account ends. If this company is claiming for the first time, or hasn't claimed within the past 3 years, it must submit the ANF by 30 September 2026.

Longer periods of account

A period of account can exceed 12 months, covering multiple accounting periods. The claim notification window is the same for all accounting periods within that longer period, and you only need to submit the form once.

For example, a company's period of account runs from 1 January 2024 to 30 June 2025, spanning two accounting periods: 1 January 2024 to 31 December 2024, and 1 January 2025 to 30 June 2025. The claim notification window opens on 1 January 2024 and closes on 31 December 2025 — 6 months after the longer period of account ends. One ANF covers both accounting periods.

Accounting period vs period of account

An accounting period is the period covered by a Company Tax Return (CT600) and cannot exceed 12 months. A period of account is the period covered by a company's financial statements and can be longer. In the vast majority of cases, they're the same.

What if you're making claims for multiple periods?

Unfortunately, if you are looking to take advantage of HMRC’s two-year deadline for R&D tax credit claims, the ANF requirement will make it difficult to claim for more than the most recent period. This is because your claim was not made within the three years before the end of the claim notification period for an earlier period.

For example, if you claim for an accounting period ending 31 December 2025 by submitting your ANF before the deadline and claiming in 2026, any earlier periods are still not available to claim. The period ending 31 December 2024 is ineligible, as your claim would’ve had to have been made within the three years before the claim notification period end date, 30 June 2025.

What information do you need to provide?

The form is straightforward to complete. You'll need:

• Your company's Unique Taxpayer Reference (UTR), which must match the one shown in your Company Tax Return
• The name, role, telephone number, and email address of the senior internal R&D contact responsible for the claim (typically a company director)
• Contact details for all agents involved in the claim, including name, business name, principal place of business address, email address, telephone number, agent reference number, and their role (R&D claim only, or R&D and other tax matters)
• Accounting period start and end date
• Period of account start and end date
• The number of R&D projects in the period
• A high-level overview of the planned R&D activities — sufficient to show that the work meets HMRC's definition of R&D, but you don't need to provide evidence at this stage

Worth noting: you won't be able to access the form once it's been submitted, so save a copy before you do.

Making your claim

Failing to submit the ANF by the deadline means your claim is invalid, no matter how much qualifying work you carried out. It can easily happen to first-time claimants, but also to experienced claimants who are unfamiliar with the three-year counting rules or the amended returns exception.

Myriad's Advance Notification Form Checker confirms your specific deadline and whether you're required to submit at all, in a few steps, at no cost. It's a good place to start before anything else.

If you have questions about how the notification requirement applies to your circumstances, contact Myriad's team to discuss your claim.