CT600C workflow

CT600C group relief consent evidence, without a weak file trail.

A practice guide for checking group relief claims, consent notices, carried-forward group relief, replacement claims, and the CT600C evidence pack before a Company Tax Return is filed.

Why consent evidence is the real CT600C control

CT600C is often treated as a numbers page: claimant company, surrendering company, period, amount, and tax reference. In practice, the bigger risk is whether the file proves that the claimant was entitled to include the claim and that the surrendering company agreed to the amount.

HMRC guidance says group and consortium relief claims are made in the Company Tax Return. Where the relevant simplified arrangement is not in force, the claimant normally needs a copy of each surrendering company's notice of consent to the claim. That makes CT600C a coordination problem as much as a tax-computation problem.

What to capture before the return is approved

A useful practice workflow should make the consent position visible before partner sign-off. Do not leave this as a loose email in the client file if the CT600C figure is material.

  • Claimant company name, UTR, accounting period, and CT600 period being filed.
  • Surrendering company name, tax reference, accounting period, and the amount surrendered.
  • Whether the claim is current-year group relief, consortium relief, carried-forward group relief, or another CT600C category.
  • Evidence that the surrendering company has capacity to surrender the amount claimed.
  • The consent notice or simplified-arrangement basis relied on by the claim.
  • Any management review note explaining partial claims, apportionments, or group allocation decisions.

Carried-forward losses need separate attention

CT600C is not only for straightforward current-year claims. HMRC's CT600C guidance includes claims to group relief for carried-forward losses and asks for consent evidence unless a simplified arrangement applies. That can catch teams out because the underlying loss history may sit outside the current-period trial balance.

Before filing, check that the loss schedule, CT600C entries, Corporation Tax computation, and client approval pack all tell the same story. If carried-forward amounts have been used in earlier periods, the evidence should show the remaining pool and why the current claim is available.

Replacement claims and amendments

HMRC's COTAX manual explains that group relief claims must be included in the CT600, and that where a company has already filed, claims are made by amending the return. It also notes that a group relief claim cannot simply be amended: it must be withdrawn and replaced by a new claim.

For practices, that means an amended CT600C should not be treated as a casual edit. The approval file should show what was withdrawn, what replaced it, who approved the replacement, and whether the surrendering-company consent still supports the revised claim.

How Robocount supports the review

Robocount treats CT600C as part of the return package: main CT600, supplementary-page indicator, computation, attachments, client approval evidence, and filing readiness. The goal is not just to populate a form. It is to give the reviewer enough structure to spot mismatches before submission.

  • Keeps CT600C entries tied to the relevant company and accounting period.
  • Surfaces claimant and surrendering company detail in the supplementary-page review.
  • Supports a clearer audit trail for consent notices and carried-forward group relief claims.
  • Helps practices review the CT600C page alongside the main tax computation and client approval pack.
  • Fits browser-based practice workflows and API-led Corporation Tax filing processes.

Practice checklist

  • Confirm CT600 box 105 indicates CT600C where the supplementary page is included.
  • Trace each CT600C amount back to the computation and working papers.
  • Check the claimant and surrendering company periods line up with the relief claimed.
  • Confirm consent notices or simplified-arrangement evidence before client approval.
  • Keep replacement-claim evidence separate from the original claim if an amendment is needed.

FAQ

Does every CT600C claim need a consent notice attached?

Not always. HMRC guidance recognises simplified arrangements in some cases. Where no simplified arrangement applies, the claimant should keep or attach the relevant surrendering-company notice of consent as required by the CT600C guidance.

Can a group relief claim be changed after filing?

HMRC manual guidance says a claim that has already been made is withdrawn and replaced, rather than simply edited. In practice, treat that as a new approval event with fresh evidence.

Is CT600C only for large groups?

No. Small groups can still have group relief issues, especially where one company has losses and another has taxable profits. The workflow still needs claimant, surrendering company, consent, and computation evidence.

Useful HMRC references

This guide is general product and filing workflow information, not tax advice. Check current HMRC guidance and the specific facts of the group before filing.