This week’s miscellaneous updates – 5 May 2026

In this week’s detailed miscellaneous updates which you can read more about below, HMRC has published guidance on completing a new CT600 supplementary return form for claiming creative industries tax reliefs or expenditure credits, the national insurance replacement credits service has been delayed until April 2027, and HMRC has established a new stakeholder working group for the implementation of Pillar Two.

In addition to the above, readers should also note the following:

• The latest HMRC Stakeholder Digest is available, in addition to the second quarterly update on the work of HMRC’s Tax Administration Reform for Compliance team,
• A new calculator has been published to deal with calculating the hybrid rate of writing down allowances in the main pool which reduced from 18 per cent 14 percent on 1 April 2026 for Corporation Tax and 6 April 2026 for Income Tax. The calculator can be used when a business has an accounting period straddling the date that this rate reduced,
• The minutes from the February 2026 meeting of HMRC’s Guidance Strategy Forum have been published,
• The latest schedule of HMRC Talking Points live and recorded webinars for tax agents are available for booking. Spaces are limited, so take a look now and save your place, and finally,
• Check HMRC’s online services availability page for details of planned downtime and the online services affected.

Creative industries tax reliefs: new supplementary CT600 return form

From 6 April 2026, companies claiming creative industries tax reliefs or expenditure credits must include the new CT600P supplementary return form pages when submitting their CT600 corporation tax return. HMRC has also published guidance on how the complete these pages. 

HMRC is also aware of an ongoing validation issue with the CT600P and has therefore advised that this will not be fixed until April 2027. As result guidance is available on what to do in corporation tax returns which are submitted before then.

National insurance replacement credits service delayed

The national insurance replacement credits service has been delayed until April 2027. According to HMRC, most eligible parents and carers will not be affected by the delay to the service and will still be able to apply for credits when the service opens next April 2027.

Anyone who believes they will suffer a financial loss due to this delay can check their position with HMRC. If there is a financial loss, the individual can report it to HMRC by following the HMRC complaints process. Guidance has also been published on how to report a financial loss.

New HMRC Pillar Two stakeholder working group

As part of the Government’s commitment set out in the Corporate Tax Roadmap to maintain an open and collaborative approach to tax policymaking, HMRC, in partnership with HM Treasury, is establishing a formal stakeholder working group on the UK’s implementation of the Pillar Two Global Minimum Tax. This working group will create a structured forum for stakeholders to contribute practical insights and discuss wider technical matters relevant to the design and operation of the regime. The aim of this collaboration is also to help identify solutions that support clarity, reduce uncertainty, and ensure the rules operate as intended.  

Further details on the scope and operation of the working group are available on GOV.UK. If you are interested in joining the working group, please email pillar2workinggroup@hmrc.gov.uk with the names and email addresses of up to two individuals you would like to nominate as delegates. 

At present one of the Government’s main priorities is to introduce the side-by-side package into UK domestic legislation. As part of this the Government will be consulting on the draft legislation with members of the Pillar Two working group.

Technical queries seeking HMRC’s view on how the legislation applies should continue to be sent to pillar2mailbox@hmrc.gov.uk and to the relevant Customer Compliance Manager (CCM) if the group has one.