What CT600J is for

CT600J is the HMRC supplementary page for disclosure of tax avoidance schemes. HMRC guidance says to complete the page where the company is party to notifiable arrangements, has received an 8-digit scheme reference number, and expects to receive a tax advantage from those arrangements.

The page also covers promoter reference number cases involving monitored promoters. That makes CT600J a compliance-sensitive page: the filing team needs to know what was disclosed, why, and whether separate reporting is needed if the return route is not enough.

When CT600J may be needed

CT600J is not a general tax planning note. It is used where specific disclosure conditions are met and scheme or promoter reference information needs to be reported with the Company Tax Return.

The company is party to notifiable arrangements.
The company has received an 8-digit scheme reference number.
The company entered into a transaction forming part of the arrangements in this or a previous accounting period.
The company expects a tax advantage from those arrangements in this or a future accounting period.
The company has a promoter reference number from a monitored promoter and expects a relevant tax advantage.

When CT600J is usually not the right page

CT600J is not a place to describe ordinary tax planning, uncertain positions, or every transaction with a tax effect. The review should separate notifiable arrangements and monitored-promoter cases from normal Corporation Tax judgments that belong in the computation, white-space disclosure, adviser files, or separate correspondence.

That boundary is important because a CT600J entry implies a specific disclosure regime. If the team concludes CT600J is not required, the working paper should still say what was checked, especially where there was a scheme discussion, prior-year disclosure, or adviser note.

What information belongs in the CT600J review

A good CT600J workflow should force the disclosure detail into the review pack rather than relying on someone remembering that a DOTAS or monitored-promoter issue exists.

Company name, tax reference, and accounting period.
Scheme reference number entries.
The accounting period in which the expected tax advantage arises.
Promoter reference number detail where relevant.
Whether any employment-related disclosure needs a separate AAG8 process.
Whether late or missing return disclosure means a separate AAG4, AAG3, or AAG4(PRN) route is needed.

Main CT600 consequences to check

CT600J should be reviewed against the main return because the disclosure is tied to an expected tax advantage. The reviewer should be able to connect the scheme or promoter reference to the affected tax treatment, the accounting period in which the advantage is expected, and any separate reporting route that is still required.

Does the expected tax advantage appear in the same period, a later period, or both?
Are scheme reference numbers and promoter reference numbers recorded exactly as supplied?
Does the CT600J indicator match the supplementary page included in the filed package?
Has the team checked whether CT600J is enough or whether a separate AAG form is still needed?

Common CT600J workflow traps

The first trap is treating CT600J as a simple free-text disclosure. HMRC guidance is specific about scheme reference numbers, promoter reference numbers, periods in which the tax advantage is expected to arise, and the circumstances where separate forms may be needed.

The second trap is assuming that a scheme disclosed in an earlier return can be ignored. HMRC guidance says the reference number may still need to be entered unless the company no longer expects any tax advantage to arise from the notifiable arrangements in the current or later accounting periods.

A third trap is leaving the decision with only one person. CT600J is sensitive enough that the preparer, reviewer, and client approval trail should all show what was disclosed and why.

Example review scenarios

If the company has received a scheme reference number and expects a Corporation Tax advantage in the period, CT600J should be reviewed alongside the computation line that reflects that advantage. If the scheme was disclosed in a prior year, the team should still check whether the expected advantage continues into the current or later accounting periods.

If an adviser has considered a planning point but no notifiable arrangement, scheme reference number, promoter reference number, or relevant tax advantage condition applies, CT600J may not be the right disclosure route. The review file should keep that reasoning visible.

How Robocount handles CT600J workflow

Robocount keeps CT600J in the Corporation Tax review workflow so disclosure entries remain visible with the main CT600, computations, client sign-off, and filing output.

Captures CT600J scheme and promoter disclosure detail for review.
Keeps the supplementary-page indicator aligned with filed output.
Connects scheme reference entries to the accounting period being filed.
Supports reviewer notes around tax advantage and separate-reporting checks.
Helps practices avoid burying avoidance disclosure decisions in disconnected working papers.

Evidence trail to keep with the return

Scheme reference numbers, promoter reference numbers, and source documents.
Working paper showing the expected tax advantage and affected accounting period.
Prior-year disclosure check where the arrangement has appeared before.
Conclusion on whether separate AAG reporting is required.
Reviewer and client approval notes for the disclosure position.

Review checklist before filing

Confirm whether any notifiable arrangements or monitored-promoter references apply.
Check scheme reference numbers and expected tax-advantage periods.
Review whether the disclosure has appeared in prior returns and whether it still needs reporting.
Consider whether separate AAG forms are required because of timing, employment-related arrangements, or promoter issues.
Make sure the CT600 indicator and CT600J output agree before submission.
Record why CT600J is included, or why a reviewed planning point does not need it.

FAQ

Is CT600J only for DOTAS?

DOTAS scheme reference number cases are central, but HMRC's CT600J guidance also covers promoter reference numbers from monitored promoters where the relevant conditions apply.

Do prior scheme disclosures ever need to be repeated?

They can. HMRC guidance says a reference number may need to be entered even if it was included on an earlier return, unless no tax advantage is expected from the arrangements in the current or later periods.

Why does CT600J need a careful workflow?

The page is compliance-sensitive and penalty-heavy. The return should show a clear trail for scheme references, expected tax advantage periods, and any separate reporting decisions.

Useful HMRC references

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

CT600J: DOTAS, scheme reference numbers, and avoidance disclosure review.