CT600C guide

CT600C group relief claims, surrenders, and consent checks.

A practical guide for accounting practices preparing Corporation Tax returns with group relief, consortium relief, carried-forward loss claims, and the CT600C supplementary page.

What CT600C is for

CT600C is the Company Tax Return supplementary page for group and consortium relief. It is used where a company claims or surrenders relief under the group relief rules, including certain carried-forward loss cases and unrelieved foreign tax provisions.

HMRC's Company Tax Return guide connects the main CT600 back to CT600C. For example, box 310 for group relief should agree with CT600C box C10, and box 312 for group relief for carried-forward losses should agree with CT600C box C130. That makes CT600C a working-paper and review problem, not just a form-filling problem.

When CT600C normally appears

CT600C is relevant when one company in a group uses losses or other eligible amounts surrendered by another company, or when a company surrenders amounts to another group member. It can also appear in consortium relief cases and in carried-forward group relief claims.

For practices, the common questions are:

  • Which company is the claimant and which company is the surrendering company?
  • Which accounting period does each claim or surrender relate to?
  • Is the claim for current-period group relief or carried-forward group relief?
  • Does the main CT600 figure agree with the CT600C total?
  • Is a notice of consent needed, and has it been retained with the file?

Why consent evidence matters

HMRC guidance says a group relief claim must be accompanied by the surrendering company's notice of consent unless a simplified arrangement is in force. That consent is not an afterthought. It is the evidence that links the amount in the claimant company's return to the surrendering company's position.

A good CT600 workflow should therefore keep the claim amount, surrendering company, accounting period, tax reference, and consent status visible together. If the file is reviewed months later, the reviewer should not have to reconstruct the group relief trail from emails and spreadsheets.

Current-period group relief

Current-period group relief usually starts from a loss or eligible amount in one group company and a taxable profit in another. The claimant company records the relief in the main CT600 and CT600C, while the surrendering company records the amount it has surrendered.

The risk is mismatch: the claimant's figure, the surrendering company's figure, the consent notice, and the computation can all drift if the numbers are edited late in the job. Robocount's review flow is designed to keep those values visible before submission.

Group relief for carried-forward losses

Carried-forward group relief can be more sensitive because it depends on the loss history and the rules for using post-2017 carried-forward losses. HMRC's CT600C guidance has separate sections for claims and surrenders of carried-forward losses.

In practice, this is where firms benefit from structured data entry. The return needs to show the relevant companies, accounting periods, tax references, and amounts, while the computation explains the loss position and restrictions.

What accountants should review before filing

  • Confirm the group relationship and the accounting periods covered by the claim.
  • Check the claimant company has sufficient taxable profits after other reliefs.
  • Check the surrendering company has an eligible amount available to surrender.
  • Reconcile CT600 box 310 or box 312 to the relevant CT600C totals.
  • Retain consent notices or confirm the simplified arrangement position.
  • Review carried-forward loss claims separately from current-period claims.
  • Make sure late changes to the computation still agree with CT600C.

How Robocount handles CT600C workflow

Robocount treats CT600C as part of the Corporation Tax return package. The supplementary page is connected to the computation, CT600 relief boxes, review trail, and HMRC filing output.

  • Connects group relief figures to the CT600 computation and main return boxes.
  • Tracks claimant and surrendering company detail for each claim or surrender.
  • Supports carried-forward group relief claim and surrender sections.
  • Keeps consent and simplified-arrangement review points visible.
  • Gives practices a clearer review path before submitting the CT600 package.

FAQ

Do I need CT600C if a company claims group relief?

Usually, yes. HMRC guidance says companies claiming or surrendering amounts under the group relief provisions need to complete CT600C. Check the current return guidance and the company's facts before filing.

Does CT600C cover carried-forward group relief?

Yes. CT600C includes separate parts for claims and surrenders of group relief for carried-forward losses.

What should agree between CT600 and CT600C?

HMRC's Company Tax Return guide says the group relief figure in CT600 box 310 should equal CT600C box C10, and the group relief for carried-forward losses figure in CT600 box 312 should equal CT600C box C130.

Is a consent notice always needed?

HMRC guidance says a group relief claim must be accompanied by a notice of consent from the surrendering company unless a simplified arrangement is in force.

Useful HMRC references

This guide is general product and filing workflow information, not tax advice. Check the latest HMRC guidance and the group position before submitting a return.