Why CT600A matters

Many UK owner-managed companies have a director's loan account. That is normal. The filing problem starts when the company is a close company and money has gone out to a director, shareholder, or connected person in a way that counts as a loan to a participator.

In that situation, the CT600 is not only the main Corporation Tax return. The company may also need CT600A, the supplementary page for close company loans and arrangements to confer benefits on participators.

What is CT600A?

CT600A is an HMRC supplementary page attached to the Company Tax Return. It is used for close company loans and arrangements to confer benefits on participators.

In plain English, CT600A is where the company reports relevant loans and calculates any tax payable on those loans. It is not a personal Self Assessment page for the director. It is part of the company's Corporation Tax return package.

The main CT600 also has boxes that connect to CT600A. For example, HMRC's Company Tax Return guide links tax payable on loans to participators from CT600A back into the main return. That is why the supplementary page and the main CT600 need to agree.

When an overdrawn director's loan becomes a CT600A issue

A director's loan account can become a CT600A issue when the company is a close company and the borrower is a participator, or an associate of a participator.

HMRC guidance treats an overdrawn current or loan account as one way a participator can incur a debt to a close company. For many small companies, the practical trigger is an overdrawn director's loan account at the year end, or a loan made during the accounting period that is not cleared in time.

The filing question is not simply "did the director take money?" It is:

Is the company a close company?
Is the borrower a participator or connected to one?
Was there a loan, advance, overdrawn account, release, write-off, or benefit arrangement?
What was outstanding at the end of the accounting period?
What was repaid, released, or written off after the period end?
Was anything still outstanding 9 months and 1 day after the end of the accounting period?

Those details affect both disclosure and tax.

What is section 455 tax?

Section 455 tax is the Corporation Tax charge that can apply to close company loans to participators. The company pays it. It is separate from ordinary Corporation Tax on profits, and it may later be reclaimed when the loan is repaid, released, or written off, subject to the timing and claim rules.

For directors and practice clients, the commercial issue is cash flow. An overdrawn loan account can create a Corporation Tax payment even where the company has already paid tax on its trading profits.

The nine-month timing trap

The key date is usually 9 months and 1 day after the end of the Corporation Tax accounting period. If a relevant loan is still outstanding after that point, section 455 tax may be due.

Repayments need careful review. HMRC guidance includes rules for cases where a loan is repaid and similar amounts are borrowed again shortly before or after repayment. Do not assume that briefly clearing an overdrawn loan account just before the deadline fixes the tax position.

What accountants need from CT600A software

CT600A is not just a single number on a form. A useful Corporation Tax workflow should collect enough detail to support the return and explain the result to the client.

The company and accounting period covered by the supplementary page.
Each relevant participator or associate.
The amount of each loan or advance.
Repayments, releases, and write-offs.
Dates that matter for the nine-month test.
Any tax payable under section 455.
Any relief being claimed where a loan has later been repaid.

For accountancy practices, this is also an audit-trail problem. If a client asks why CT600A was included, the file should show the loan movement, repayment timing, review decision, and how the figure reached the return.

How Robocount handles CT600A workflow

Robocount is built around the CT600 workflow, not only the headline Corporation Tax number. CT600A is treated as part of the filing package: main CT600, supplementary pages, computation, iXBRL attachments, review trail, and HMRC submission readiness.

Tracks loan and arrangement entries for the accounting period.
Connects CT600A to the supplementary-page indicator in the CT600 review flow.
Surfaces repayment, release, write-off, and relief details for review.
Keeps CT600A figures visible alongside the main Corporation Tax return.
Gives practices a clearer trail for owner-managed company edge cases.

FAQ

Do I need CT600A if my director's loan account is overdrawn?

Possibly. If the company is a close company and the overdrawn account is a loan to a participator or an associate, CT600A may be needed as part of the Company Tax Return. The details depend on the amount, timing, repayments, and whether anything remains outstanding after the relevant deadline.

Is CT600A for the company or the director?

CT600A is part of the company's Corporation Tax return. The director may also have personal tax or benefit-in-kind consequences depending on the facts, but CT600A itself is a company filing page.

Can the company reclaim section 455 tax?

HMRC says close companies can claim relief when the relevant loan or value is repaid, released, or written off. The timing of the claim matters, so keep the repayment and claim dates visible in the working file.

Does repaying the loan before the deadline always solve it?

Not always. HMRC guidance includes rules for situations where loans are repaid and similar amounts are borrowed again. If a director's loan is material, get the dates and amounts right before filing.

Useful HMRC references

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

CT600A: directors' loan accounts, close company loans, and your CT600.