CT600 Box 550: Land Remediation Credit

CT600 Box 550 is where companies enter their Land Remediation Credit — a payable tax credit available to loss-making companies that have incurred qualifying expenditure cleaning up contaminated or derelict land. This is a specialist relief for companies in property development, housebuilding, construction, or urban regeneration.

If your company has not acquired and remediated contaminated or derelict land, Box 550 will not apply and should be left blank.

What Is CT600 Box 550?

Box 550 appears in the Tax Payments and Overpayments section of the CT600 form. It captures specifically the payable tax credit element of Land Remediation Relief — available only to companies that are in a loss-making position and elect to surrender part of that loss in exchange for a cash payment from HMRC.

Land Remediation Relief itself has two components, depending on whether your company is profitable or loss-making:

For profitable companies: You receive an enhanced deduction of 150% of qualifying expenditure. This means you deduct the actual cost of remediation work plus an additional 50% uplift, reducing your taxable profits and therefore your Corporation Tax bill.

For loss-making companies: You can surrender the part of your loss attributable to the enhanced deduction — known as the qualifying land remediation loss — and receive a cash tax credit from HMRC at a rate of 16% of the loss surrendered.

Box 550 is specifically for the second scenario: the 16% payable credit claimed by loss-making companies. Profitable companies benefit through the enhanced deduction, which flows through their profit and loss computation, rather than through Box 550.

What Is Land Remediation Relief?

Land Remediation Relief (LRR) was introduced in 2001 to address market failure in the development of contaminated land. It was subsequently extended in 2009 to cover long-term derelict land. The relief recognises that the cost of cleaning up damaged or abandoned sites is a significant barrier to development, leaving brownfield land unused when it could otherwise support housing, commercial, or public use.

The relief is governed by the Corporation Tax Act 2009, Part 14, building on the original provisions in the Finance Act 2001. It applies to companies within the charge to UK Corporation Tax — individuals and general partnerships cannot claim, though company members of a partnership may claim their share.

What Types of Land Qualify?

There are two categories of qualifying land:

Contaminated land — land containing harmful substances or in a state where harm could be caused to people, controlled waters, or ecosystems. This includes industrial pollutants such as asbestos, heavy metals, petroleum products, solvents, and chemicals. It also covers naturally occurring contaminants such as arsenic and radon where these exceed threshold levels.

Derelict land — land that is out of productive use and cannot be brought back into use without first demolishing structures, clearing surface debris, or removing contamination left by previous industrial activity. From April 2009, the definition of derelict land was broadened to include land that has been out of use for an extended period.

Special provisions also apply to certain biological hazards, including Japanese knotweed, where its removal is necessary to enable development.

A site does not need to meet both definitions — it qualifies if it falls under either contaminated or derelict land. However, the two categories have different qualifying criteria, so you must identify which applies to your site.

Who Qualifies for Land Remediation Relief?

To claim Land Remediation Relief and use Box 550, your company must meet all of the following conditions:

Be a UK company liable to Corporation Tax — the relief is not available to individuals, general partnerships, or exempt organisations
Have acquired the land from an unconnected third party — companies cannot claim if they are the party responsible for the contamination, or if the land was acquired from a connected party who caused the contamination
Have incurred qualifying remediation expenditure — costs that would not have been incurred had the land not been in a contaminated or derelict state
Not have been subsidised for the expenditure — amounts covered by grants, public funding, or other state aid are excluded

The restriction on claiming where you caused the contamination is fundamental to how the relief works. It is specifically designed to encourage new investors to clean up land left damaged by previous industrial owners. If your company operated a factory on a site for decades and contaminated the ground, you cannot use LRR to recover the clean-up cost when you later want to redevelop it.

What Expenditure Qualifies?

Qualifying Land Remediation Expenditure (QLRE) includes costs that are directly attributable to remediating the land:

Staffing costs — wages and employer's National Insurance for employees directly carrying out remediation work
Materials — consumables and materials used in the remediation process (site investigation materials, containment barriers, soil treatments, etc.)
Subcontractor costs — payments to unconnected third parties carrying out remediation work on your behalf
Connected subcontractor costs — payments to connected companies are allowed in limited circumstances, subject to conditions

Expenditure must be directly attributable to the remediation itself. General site investigation costs, project management overhead, planning fees, or development costs that would have been incurred regardless of contamination do not qualify.

The Enhanced Deduction: How It Works

For profitable companies, the enhanced deduction reduces the Corporation Tax bill by allowing a 150% deduction on qualifying costs.

For example: if a property developer spends £200,000 cleaning up contaminated land, it can deduct £300,000 (150% of £200,000) from its trading profits. At a Corporation Tax rate of 25%, the extra £100,000 deduction saves £25,000 in Corporation Tax compared with a normal 100% deduction.

This enhanced deduction flows through the company's tax computation rather than through Box 550. Profitable companies will see the benefit in a lower figure in CT600 Box 440: Corporation Tax Payable.

The Payable Credit: How Box 550 Works

Loss-making companies can elect to surrender their qualifying land remediation loss — the portion of the period's loss attributable to the enhanced deduction — in exchange for a cash payment from HMRC.

The credit rate is 16% of the qualifying loss surrendered.

For example: a company has a qualifying land remediation loss of £150,000 in the period. It surrenders this loss to HMRC and receives a cash tax credit of £24,000 (16% × £150,000). This figure is entered in Box 550 of the CT600.

The surrendered loss cannot then be carried forward or used in any other way — surrendering it for the credit replaces the loss carry-forward benefit. Companies should therefore consider which option is more valuable: taking the 16% cash credit now, or carrying the loss forward to offset future profits at the prevailing Corporation Tax rate.

How to Claim

Claiming Land Remediation Relief involves the following steps:

Identify qualifying expenditure — compile all costs that meet the QLRE conditions and separate them from general development spend
Calculate the enhanced deduction — multiply qualifying expenditure by 150% and include this in your tax computation
Determine your position — if profitable, the enhanced deduction reduces your CT bill automatically. If loss-making, consider whether to surrender the qualifying loss for the 16% credit
If claiming the credit, enter it in Box 550 — include the payable credit amount on your CT600
Prepare a supporting computation — HMRC requires a computation demonstrating the relief claim. Submit this alongside your return

For capital expenditure on remediation, companies must make an election to treat it as a revenue deduction rather than capitalising it. This election must be submitted within two years of the end of the accounting period. Missing this deadline means you cannot reclassify capital spend as qualifying QLRE.

All claims must be made within six years of the accounting period end, so there is some flexibility to amend returns and add a claim retrospectively if remediation costs were overlooked at the time of filing.

Common Mistakes to Avoid

Claiming where you caused the contamination — This is the most common disqualifying error. If your company or a connected party contaminated the land, you cannot claim Land Remediation Relief, regardless of how much was spent on clean-up.

Missing the election deadline for capital expenditure — Capital spending requires a specific election within two years. Many companies miss this and lose the ability to include significant remediation costs.

Including development costs — Costs that would have been incurred regardless of contamination — site clearance, normal excavation, standard demolition — do not qualify. Only the incremental costs directly caused by the contamination or dereliction count.

Including subsidised expenditure — Grants or public funding received for the remediation work must be deducted from qualifying expenditure. Failure to do this can result in HMRC challenging the claim.

Not keeping adequate records — HMRC expects evidence of what work was done, why it was necessary due to contamination, and how costs were allocated. Contemporaneous records from site assessments and environmental reports are essential.

Who Typically Claims Land Remediation Relief?

Land Remediation Relief is most relevant to companies involved in:

Property development — buying brownfield sites for residential or commercial development
Housebuilding — developing former industrial or commercial sites for housing
Regeneration — urban renewal projects repurposing disused land
Commercial real estate — acquiring industrial or retail sites requiring environmental clean-up before redevelopment

It is a relatively specialist relief. If your business regularly acquires and develops brownfield land, a specialist property tax adviser can help ensure you capture all qualifying expenditure and make claims within the correct time limits.

To understand how enhanced deductions affect your overall tax computation, see our guide to CT600 Box 235: Adjusted Trading Profit.

For a full picture of how Corporation Tax is calculated and the role of credits and reliefs in the final payment figure, see CT600 Box 440: Corporation Tax Payable.

Summary

CT600 Box 550 captures the payable Land Remediation Credit for loss-making companies that have spent money cleaning up contaminated or derelict land acquired from an unconnected party. The broader Land Remediation Relief system gives profitable companies a 150% enhanced deduction and gives loss-making companies a 16% payable credit on the qualifying loss they surrender. Claims are time-limited, and the relief excludes companies that caused the contamination themselves. Given the complexity of qualifying expenditure rules, specialist advice is recommended for anyone regularly developing brownfield sites.