CT600K Restitution Tax

CT600K Tax Return Form for Restitution Tax

You need to complete these supplementary pages if:

  • the company is chargeable to corporation tax on restitution interest under Part 8C of CTA 2010 and
  • has restitution interest that is not exempt from the restitution tax charge.

Restitution interest means profits in relation to which Conditions A to C below are met.

Condition A - is that the profits are interest paid or payable by the Commissioners in respect of a claim by the company for restitution with regard to either of the following matters (or alleged matters)

  • the payment of an amount to the Commissioners under a mistake of law relating to a taxation matter, (or alleged matters)
  • the unlawful collection by the Commissioners of an amount in respect of taxation.

Condition B - is that a court has made a final determination that the Commissioners are liable to pay the interest or the Commissioners and the company, have in final settlement of the claim, entered into an agreement under which the company is entitled to be paid, or is to retain, the interest.

Condition C - is that the interest determined to be due, or agreed upon, is not limited to simple interest at a statutory rate.

Please check if you’re required to submit this form online

Find out more about who must submit an online Company Tax Return.

Further details of the meaning of restitution interest can be found in S357YC of CTA 2010.

Corporation tax is charged on restitution interest at the restitution payments rate. The restitution payments rate is currently 45%.

Corporation tax reliefs and any amounts of income tax or corporation tax, or any other amounts, which may be set off against a company’s overall liability to income tax and corporation tax for an accounting period are excluded. See S357YL CTA 2010.

An amount deducted from an interest payment is treated for all purposes as paid by the company on account of the company’s liability. See S357YO CTA2010.

For further information read ‘What supplementary pages do I need to complete and include as part of the Company Tax Return?’ to find out what supplementary pages you need to complete.


The following information is required:

  • K1 - Company name: Enter the name of the company.
  • K2 - Tax reference: Enter the company’s 10 digit unique taxpayer reference.
    Period covered by this supplementary page (cannot exceed 12 months)
  • K3 - from DD MM YYYY: Enter the start date of the accounting period.
  • K4 - to DD MM YYYY: Enter the end date of the accounting period.

Tax calculation

Details of tax calculation.

  • K5 - Self–assessment of tax payable before restitution tax (copy the figure from box 525 on CT600)
  • K10 - Restitution interest (Enter the amount of the restitution interest that arises in the accounting period)
  • K15 - A (Financial year), B (Amount of interest), C (Rate of tax %), D (Tax)
  • K20 - Total restitution tax (This equals the sum of boxes 345, 360, 375, 395, 410 and 425)
  • K25 - Enter the amount of tax withheld from the payment that relates to this accounting period. See S357YO CTA 2010. The amount in this box cannot exceed the amount in box K20.
  • K30 - Self–assessment of tax payable after restitution tax (Enter the sum of box K5 and K20 minus the amount in box K25)
  • K35 - Restitution tax now payable (Enter box K20 minus box K25. Copy this figure to box 527 on the CT600)

HMRC have provided following Company tax return guide to form CT600 (2022) Version 3 for accounting periods starting on or after 1 April 2015 to assist Companies complete the Corporation tax returns. Further information can also be found on GOV.UK website.