Supplementary pages CT600M: Freeports and Investment Zones
Source: gov.uk (2025-11-21)

How to complete supplementary pages CT600M and what information you need to include.

When to complete

Complete these supplementary pages if the company is claiming:
- enhanced structures and buildings allowances (SBA)
- enhanced capital allowances (ECA) for plant and machinery for qualifying expenditure relating to a Freeport or Investment Zone tax site
Read HMRC’s list of Freeport tax sites and the associated maps (https://www.gov.uk/government/collections/maps-of-freeports-and-freeport-tax-sites) for more information.

Company information

M1 Company name

Enter the company name.

M2 Tax reference

Enter the company’s 10-digit Unique Taxpayer Reference.

Period covered by this supplementary page (cannot exceed 12 months)

M3

Enter the start date using the format DD MM YYYY.

M4

Enter the end date of the accounting period using the format DD MM YYYY.

Enhanced structures and buildings allowances in Freeports and Investment Zones

M5

Make a separate entry for claims relating to each building or structure for which a claim is being made.

Column A Location of Freeport or Investment Zone

Only enter the number corresponding to the location of the Freeport or Investment Zone:
- Freeport: East Midlands Airport — 1
- Freeport: Felixstowe and Harwich — 2
- Freeport: Humber — 3
- Freeport: Liverpool City Region — 4
- Freeport: Plymouth and South Devon — 5
- Freeport: Solent — 6
- Freeport: Thames — 7
- Freeport: Teesside — 8
- Freeport: Inverness and Cromarty Firth — 9
- Freeport: Forth — 10
- Freeport: Anglesey — 11
- Freeport: Celtic (Port Talbot and Milford Haven) — 12
- Investment Zone: Liverpool City Region — 13
- Investment Zone: North East — 14
- Investment Zone: West Midlands — 15
- Investment Zone: East Midlands — 16
- Investment Zone: Flintshire and Wrexham — 17
Column B Address of business operation

Enter the address of the business operation.

Column C Date structure or building was brought into qualifying use

Enter the later of the date that the structure or building you are claiming for was brought into qualifying use, or the qualifying expenditure was incurred.

Column D Date of first contract for construction

Enter the date of the first contract for construction. Where no contract is entered into, or the contract is entered into only after construction works commence, enter the date the construction works commence.

Column E Total amount of qualifying expenditure

Enter the total amount of Freeport or Investment Zone qualifying expenditure relating to a building or structure if you are the first claimant and claiming structures and buildings allowance for the first time in respect of that amount of Freeport or Investment Zone qualifying expenditure, this qualifying expenditure must be reflected in an allowance statement. If you incurred the qualifying expenditure and have previously entered the expenditure alongside your first claim to SBA then enter 0. If you are a subsequent owner of the structure or building and a previous owner has claimed SBA then you should enter 0 (assume that a previous owner has claimed SBA and returned the qualifying expenditure unless you know otherwise).

Where an apportionment has been made, do not include the amount of non-Freeport or non-Investment Zone qualifying expenditure. This expenditure should be reported on your CT600 in the normal way.

Column F Total Structures and Buildings Allowance (SBA) claim amount

Enter the total enhanced Structures and Buildings Allowance claim amount. Where an apportionment has been made for properties straddling a tax site, do not include the amount of non-enhanced structures and buildings allowances claimed. This claim amount should be reported on your CT600 in the normal way.

M10 Totality of amounts of qualifying expenditure

Enter the total of column E.

This amount must also be included in box 771 of your CT600 form.

M15 Totality of structures and buildings allowances claim amounts

Enter the total of column F.

This amount must also be included in box 711 (the amount relating to a trade) and to box 736 (the amount unrelated to a trade) of your CT600 form.

Enhanced capital allowance for plant and machinery in Freeports and Investment Zones

M20

A separate entry must be made for claims relating to different Freeports and Investment Zones.

Column A Location of Freeport or Investment Zone

Only enter the number corresponding to the location of the Freeport or Investment Zone:
- Freeport: East Midlands Airport — 1
- Freeport: Felixstowe and Harwich — 2
- Freeport: Humber — 3
- Freeport: Liverpool City Region — 4
- Freeport: Plymouth and South Devon — 5
- Freeport: Solent — 6
- Freeport: Thames — 7
- Freeport: Teesside — 8
- Freeport: Inverness and Cromarty Firth — 9
- Freeport: Forth — 10
- Freeport: Anglesey — 11
- Freeport: Celtic (Port Talbot and Milford Haven) — 12
- Investment Zone: Liverpool City Region — 13
- Investment Zone: North East — 14
- Investment Zone: West Midlands — 15
- Investment Zone: East Midlands — 16
- Investment Zone: Flintshire and Wrexham — 17
Column B Address of business operation

Enter the address of the business operation.

Column C Put an X in this box if you have made an Enterprise Zone claim relating to this ECA claim

Enter X if your business operation is also located within an enterprise zone and you have claimed tax relief for this investment in plant or machinery for its use, or for it being held for use, within a designated assisted area within that enterprise zone.

Column D Total amount of ECA claimed for the accounting period

Enter the total allowances claimed on the purchase of plant or machinery primarily for use in a tax site of a specific Freeport or Investment Zone. If the full allowance is claimed, this will be the total expenditure incurred.

Column E Disposal value

Enter any amount brought into account for the disposal of such plant or machinery, even if a balancing charge has not arisen due to the disposal value being brought into account in the main pool, special rate pool or a single asset pool.

Do not include the amounts in columns D and E with the other allowances and balancing charges in boxes 690 to 730 of your CT600 form (unless a disposal value has been brought into account in the main pool, special rate pool or a single asset pool, in which case it could affect the amounts entered in those boxes).

M25 Totality of amounts of ECA claimed for the accounting period

Enter the total of column D. This amount must be included with any other first-year allowance expenditure in box 760 of your CT600 form.

M30 Total of disposal values

Enter the total of column E.