What details do I need to know when organising my CT600 and computation for my R&D tax credit claim?

There are several key details every business should understand when preparing their Corporation Tax return (CT600), particularly where an R&D tax relief claim is involved.

These details help ensure the R&D claim is presented correctly and aligns with HMRC’s current submission criteria. This includes: 

• Formatting and submission – HMRC requires R&D tax credit claims to follow precise digital formatting rules. The Additional Information Form (AIF) must be submitted before the CT600 and the accompanying tax computation. If the AIF is not submitted first, HMRC will reject the claim or request the business to resubmit the documentation.
• Figures to include – When completing the CT600, the figures must clearly reflect your qualifying R&D expenditure and the calculated R&D relief or tax credit. These amounts should align with the figures shown in your tax computation and supporting technical documentation.
• Enhanced expenditure – Under the Merged R&D Scheme, qualifying R&D costs are enhanced when calculating the tax benefit. It’s vital to apply the correct enhancement rate to eligible R&D expenditure such as staff costs, software, consumables, and externally provided workers where applicable.
• Amended returns – If an R&D tax relief claim is made or revised after the original CT600 has been submitted, an amended Corporation Tax Return and revised tax computation must be filed. HMRC allows amendments within the standard timeframe given, this is typically two years from the end of the accounting period.

HMRC encourages a short project summary explaining why the work qualifies and outlining related costs. Clear, factual explanations help strengthen your claim and reduce enquiry risk.