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Submitting an Amended Corporation Tax Return to HMRC

 

Overview

If a Corporation Tax return has already been submitted to HMRC and needs to be corrected, BTCSoftware supports amended CT submissions directly to HMRC. The process differs depending on whether the original return was submitted via BTCSoftware.

 

⚠ Important: HMRC accepts amended CT returns within 12 months of the statutory filing deadline (generally 12 months after the accounting period end). Amendments outside this window must be made by writing to HMRC directly.

 

If the Original Return Was Submitted via BTCSoftware
  1. Open the CT return in BTCSoftware.
  2. From the Summary screen, click Open CT Comp & CT600.
  3. Make the required corrections to the return.
  4. Click Submit to HMRC.
  5. Follow the submission prompt — BTCSoftware will identify the prior submission and present the amended submission option.
  6. Confirm the amended submission.

 

If the Original Return Was NOT Submitted via BTCSoftware
  1. Create a new CT return in BTCSoftware for the client and accounting period.
  2. Complete the return with the corrected figures.
  3. On the Return Summary screen, click Submit to HMRC.
  4. In the submission dialogue box, tick the Enable Submit checkbox.
  5. Hold down the Shift key on your keyboard and click Submit. This forces BTCSoftware to submit as an amended return even without a prior BTCSoftware submission on record.

 

⚠ Important: Only use the Shift + Submit method where the original return was genuinely submitted outside BTCSoftware. Do not use it to force a first-time submission through as an amendment.

 

Frequently Asked Questions

Q: Do I need to reattach the accounts when submitting an amended CT return?

A: Yes. The iXBRL accounts file must be regenerated and attached before submitting the amended return. Check and Generate iXBRL File should be run after making any corrections.

Q: The 12-month amendment window has passed — can I still amend?

A: For amendments outside the window, you must write to HMRC's Corporation Tax office. Include the company name, UTR, accounting period, and a description of the correction required.