This article covers the most common errors encountered when working with Corporation Tax returns and Year End Accounts in BrightTax, with step-by-step fixes for each.

Cause: The Marginal Relief supplementary schedule is missing from the CT return. Without it, Box 329 on the CT600 is not ticked and the full 25% rate is applied regardless of profit level.

Fix:

1. Expand the CT navigation toolbar and click the Template tab.
2. Click Supplementary Schedules.
3. Tick Marginal Relief.
4. Re-run Check and Calculate.
5. The correct blended rate will now be calculated for profits between £50,000 and £250,000.

Cause: Error 4066 means HMRC has found incomplete content in the CorporationTaxChargeable element. This is most commonly caused by a missing Marginal Relief schedule or an incorrect associated companies entry on the CT600.

Fix:

1. Check that the Marginal Relief supplementary schedule is included (see above).
2. Navigate to the CT600 form and check Box 328 — this is where the number of associated companies is entered.
3. If the company has associated companies, ensure the correct number is entered in Box 328.
4. If the company has no associated companies, confirm Box 328 is blank (not zero).
5. Re-run Check and Calculate and resubmit.

Cause: The Advanced CT template has been selected for a return that does not have tangible fixed asset entries. The Advanced template requires tangible fixed asset data that is not present, causing a validation failure.

Fix:

1. Open the CT task and click the three-dot menu (⋯) on the bottom toolbar.
2. Select Discard.
3. Go to the Task List, find the discarded task, and click the red bin icon to permanently delete it.
4. Create a new CT task for the same client and period.
5. Select the Express template this time.
6. Re-enter the return data.

Cause: The depreciation figure is imported from the linked iXBRL accounts file. If the figure in the CT return does not match the accounts, the tagging in the accounts file may be incorrect.

Fix:

1. Check the depreciation figure in the linked accounts (BrightTax YEA, BrightAP, or third-party iXBRL file).
2. Ensure the depreciation is correctly tagged in the iXBRL file.
3. Once corrected in the accounts, relink or reimport the accounts into the CT return.
4. If the accounts are correct but the figure still looks wrong, switch to Edit mode on the CT computation page and manually override the depreciation field.

Cause: This occurs when using BrightTax for a client for the first time. No prior year accounts exist in the system, so the prior period cannot be defined automatically.

Fix:

1. Create a Year End Accounts task for the prior accounting period.
2. From the YEA Summary tab, select the appropriate template.
3. On the top toolbar, click Actions > Complete.
4. Click Yes on the first warning.
5. Click Skip on the second warning.
6. Return to the current year accounts — the prior period column will now be defined.

If you have deleted data in a CT return or Year End Accounts task but have not yet saved:

• Close the browser window without saving — BrightTax will revert to the last saved state.

If you have already saved after deleting:

• Unfortunately, once saved, deleted data cannot be automatically recovered.
• Reopen the task and re-enter the deleted figures.
• For future prevention: use Discard rather than deleting individual entries where possible.

If the company's registered office address has changed and needs to be updated on a CT or YEA task:

1. Open the task and go to the Address Detail tab from the left-hand menu.
2. Locate the Registered Office Address box.
3. Select the updated address from the dropdown, or click New Address to add it.
4. Click Save.

Q: I submitted a CT return and received an HMRC error — where do I find the error details?

A: HMRC error details are shown in the submission response at the point of submission and are also recorded in the Submission History tab. The error code and description will indicate what needs to be corrected.

Q: Can I recover a Year End Accounts task I accidentally deleted?

A: No. Deletion is permanent. Always discard a task rather than deleting it if you think you may need to access it again.