CT600 Supplementary Pages: Which Ones Do You Need?
The main CT600 form covers company information, income, capital gains, losses, and the Corporation Tax calculation itself. But depending on your circumstances, you may also need to file one or more supplementary pages.
Most small UK companies need none at all. Here's the complete guide.
Quick Decision Table
| Page | You Need It If... | Most Small Companies? |
|---|---|---|
| CT600A | Your company made loans or advances to directors or shareholders | Sometimes |
| CT600B | You control a foreign company or have a branch abroad | Rarely |
| CT600C | You're claiming or surrendering group relief with another group company | Rarely |
| CT600D | Your company is an insurance company | Almost never |
| CT600E | You're a charity or CASC | Rarely |
| CT600F | Your company is in the tonnage tax (shipping) regime | Almost never |
| CT600G | Your company has Northern Ireland profits | Almost never |
| CT600H | You paid cross-border royalties to non-UK companies | Almost never |
| CT600I | You have oil & gas ring fence profits | Almost never |
| CT600J | You used a disclosable tax avoidance scheme | Almost never |
Important: Losses and Capital Gains Go on the Main Form
A common misconception is that trading losses or capital gains require a supplementary page. They don't — they are reported directly on the main CT600:
- Trading losses (current-period losses, brought-forward losses, carry-back claims) go in boxes 160, 275, 285, and 780–790 of the main CT600.
- Capital gains from selling shares, property, or other chargeable assets go in boxes 210–220 of the main CT600. Companies pay Corporation Tax on their gains at the normal CT rate — there is no separate supplementary page for this.
You do not need a supplementary page simply because your company made a trading loss or sold an asset.
CT600A: Loans to Participators by Close Companies
File this if your company is a "close company" (controlled by 5 or fewer people — which covers most owner-managed limited companies) AND it made loans or advances to a director or shareholder (a "participator").
When You Need It
Common examples:
- The company lent money directly to a director
- A director took drawings that were not salary or dividends, leaving an overdrawn director's loan account
- The company paid personal expenses on a director's behalf
The S455 Tax Charge
When a close company lends money to a participator, a 33.75% tax charge applies to the outstanding loan balance under CTA 2010 s.455. This charge is due 9 months and 1 day after the end of the accounting period — the same date as your main Corporation Tax payment. The charge is reported via CT600A; the resulting tax flows to box 480 of the main CT600, with the CT600A indicator ticked in box 95.
The S455 charge is refunded when the loan is repaid to the company (CTA 2010 s.458), so if the director repays the loan in a later period, the company can reclaim the tax.
If all amounts taken from the company were salary or dividends properly declared, you don't need CT600A.
CT600B: Controlled Foreign Companies and Related Matters
File this if your company:
- Controls a company resident outside the UK (a "Controlled Foreign Company" or CFC)
- Has a permanent establishment (such as a branch office) in a foreign country and is claiming the foreign PE exemption
- Has hybrid or other mismatches — cross-border arrangements that exploit differences between countries' tax rules
The indicator box on the main CT600 is box 100.
Most small UK-only companies with no overseas subsidiaries or branches leave this blank.
CT600C: Group and Consortium Relief
File this if your company is part of a corporate group and is either:
- Surrendering losses to another group company (so a profitable company in the group can use them)
- Claiming losses surrendered by another group company to reduce your tax bill
Both the surrendering and claiming companies must complete CT600C. The indicator box on the main CT600 is box 105.
Group relief allows UK corporate groups to share losses between members. Standalone companies (no parent company, no subsidiaries) never need this page.
CT600D: Insurance Companies
File this if your company is an insurance company where policyholders' profits are charged at a rate equivalent to the basic rate of Income Tax under Section 88 of the Finance Act 1989. The indicator box is box 110.
This is a highly specialist page. Ordinary trading companies — even those that sell insurance products as agents or intermediaries — are not insurance companies in this technical sense. Most small companies leave this blank.
CT600E: Charities and Community Amateur Sports Clubs (CASCs)
File this if your organisation is a registered charity or CASC claiming exemptions on qualifying income and gains. The indicator box is box 115.
Charitable companies and CASCs are generally exempt from Corporation Tax on income and gains applied for charitable purposes, but they still need to file a return and complete CT600E to claim those exemptions.
Note: this page is for the charity itself — if your trading company makes charitable donations, those are deducted in box 305 of the main CT600 and you do not need CT600E.
CT600F: Tonnage Tax
File this if your company is in the tonnage tax regime — a special scheme for qualifying shipping companies where profits from ship operations are calculated based on net tonnage rather than actual trading profits. The indicator box is box 120.
Tonnage tax requires a formal election with HMRC. Shipping companies in this regime will know about it. Most small companies never need this page.
CT600G: Northern Ireland
File this if your company has profits from Northern Ireland activities to report on the Northern Ireland supplementary page. The indicator box is box 125.
There is no separate Northern Ireland Corporation Tax rate yet (legislation provides for one if a rate is ever set), so this page is rarely used in practice.
CT600H: Cross-Border Royalties
File this if your company paid royalties to companies in other countries — for example, patent fees, trademark licences, or software licensing payments to foreign companies. The indicator box is box 130.
Note: claiming Double Taxation Relief on overseas income received by your company is handled on the main CT600 (box 450), not through CT600H.
CT600I: Ring Fence Trades (Oil and Gas)
File this if your company has oil and gas extraction or exploration trades within the UK ring fence and is subject to the supplementary charge on those profits. The indicator box is box 135.
Virtually all small companies leave this blank.
CT600J: Disclosure of Tax Avoidance Schemes
File this if your company has used or is using a Disclosable Tax Avoidance Scheme (DTAS) — a specific marketed scheme with an HMRC Scheme Reference Number — or has been notified of a promoter reference number by an HMRC-monitored promoter. The indicator box is box 140.
This is NOT about normal tax planning like claiming capital allowances or paying salaries and dividends. It is about specific schemes that HMRC requires you to disclose. Most small companies leave this blank.
Other Supplementary Pages
Beyond CT600A–J, HMRC also has:
- CT600K: Restitution tax (for companies that received restitution interest from HMRC)
- CT600L: Research and Development tax relief (RDEC and the enhanced R&D intensive support scheme)
- CT600M: Freeports and Investment Zones
- CT600N: Residential Property Developer Tax (RPDT)
- CT600P: Creative industries tax reliefs
These are all highly specialist. If any apply to you, you will typically be working with a professional adviser familiar with the relevant scheme.
What If I'm Not Sure?
If your company is a straightforward trading company with:
- No loans or advances to directors beyond normal salary and dividends
- No group companies (no parent company, no subsidiaries)
- No overseas subsidiaries or branches
- No insurance, shipping, oil & gas, or other specialist activities
Then you likely need no supplementary pages at all — just the main CT600 form. Losses and capital gains are handled entirely on the main form.
Key Takeaways
- Most small companies need 0 supplementary pages — losses and capital gains go on the main CT600, not a supplementary page
- CT600A is for loans and advances to directors or shareholders (not losses) — one of the more commonly encountered pages for owner-managed companies
- CT600C is for group relief — standalone companies never need it
- CT600E is for charities and CASCs claiming their tax exemptions
- CT600F–J and beyond are for highly specialist situations
File Your Main CT600 with Taxpipe
Taxpipe guides you through the main CT600 return step by step — trading profits, capital allowances, losses, capital gains, bank interest, and property income. The guided wizard covers the vast majority of small UK companies, including dormant companies. Charities and CASCs can also file the CT600E supplementary page with Taxpipe.
File your CT600 → — £59 flat fee.