Why group relief evidence gets messy

Group relief and consortium relief are easy to under-document because the tax result often appears as a single relief figure in the claimant company's CT600. Behind that figure there may be several surrendering companies, different accounting periods, carried-forward loss restrictions, and notices of consent.

HMRC's CT600C guidance says CT600C is used for group and consortium relief, including claims and surrenders of carried-forward losses. HMRC's COTAX manual also says claims to group and consortium relief must be included in the company's CT600 return, and that if a return has already been submitted, group relief claims may be made by amending the return.

The minimum evidence set

A good file should let a reviewer move from the CT600 tax result back to the companies, amounts, periods, and permissions behind the claim. At minimum, keep:

Claimant company name, accounting period, tax reference, and CT600 period.
Surrendering company name, accounting period, tax reference, and amount surrendered.
Whether the claim is current-period group relief, carried-forward group relief, consortium relief, or another CT600C entry.
Working-paper reconciliation from the computation to CT600 and CT600C totals.
Notice of consent, unless a simplified arrangement is in force.
Client or group approval of the claim and any connected amendments.

Consent notices and simplified arrangements

HMRC guidance says that unless a simplified arrangement is in force, the company must attach a copy of each surrendering company's notice of consent to the claim. The COTAX manual says a group relief claim must be accompanied by a copy of the notice of consent given by the surrendering company.

In practice, consent evidence is the control that stops the claimant's CT600 from drifting away from the surrendering company's position. If the claim changes late in the job, the consent evidence should be reviewed again before filing.

Claimant company review

Check the claimant has profits against which the relief can be used.
Reconcile the claim to CT600 box 310 or carried-forward group relief to box 312 where relevant.
Check CT600C totals agree to the main CT600 and computation.
Confirm the accounting period of each surrendered amount.
Record whether the claim depends on consortium rules or a simple group relationship.

Surrendering company review

Confirm the surrendering company has an eligible amount available to surrender.
Check that the amount has not been used elsewhere or duplicated across claimant companies.
Review the surrendering company's own CT600 loss, deficit, or excess amount entries.
Keep the notice of consent or simplified-arrangement evidence with the return file.
Make sure changes in one company trigger review of the other company's return package.

Carried-forward group relief

Carried-forward group relief needs extra care because the claim relies on a loss history and the rules for using post-2017 carried-forward losses. HMRC's CT600C guidance has separate sections for claims and surrenders of group relief for carried-forward losses.

The review note should explain the loss brought forward, the amount available, any restriction, the amount surrendered, and the claimant company's use of the relief. If the computation changes, revisit CT600C rather than assuming the old claim still fits.

Amendments and replacement claims

HMRC's COTAX manual says claims to group relief cannot be amended but must be withdrawn and replaced by a new claim. For practices, that means an amendment workflow should preserve the old claim trail, the reason for withdrawal or replacement, and the new consent evidence.

Treat a changed group relief claim as a connected-file issue, not just a single-box edit. The claimant company, surrendering company, computation, CT600C, consent evidence, and client approval all need to move together.

How Robocount helps

Robocount connects the CT600C workflow to the main Corporation Tax return, computation, review trail, and submission package. That is especially useful where a practice handles multiple companies in a group or needs a clean audit trail for AI-assisted preparation.

Tracks claimant and surrendering company detail for CT600C claims.
Keeps group relief totals close to CT600 and computation review.
Supports review of current-period and carried-forward group relief sections.
Helps practices keep consent and approval evidence visible before filing.
Gives API and MCP workflows structured fields rather than buried spreadsheet notes.

FAQ

Does every group relief claim need CT600C?

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

What is the most common evidence gap?

The most common gap is weak consent evidence: the claim appears in the claimant company's CT600, but the surrendering company, accounting period, and consent trail are hard to prove later.

Can a group relief claim be changed after filing?

HMRC manual guidance says if a company has already submitted its return, it may make group relief claims by amending the return. It also says claims to group relief cannot be amended but must be withdrawn and replaced by a new claim.

Why does this matter for automated CT600 workflows?

Group relief is connected-party work. Automation can help prepare the data, but the practice still needs clear human review, consent evidence, and reconciliation across companies before submission.

Useful official references

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

Group relief claims need more than a CT600C total.