Free UK subcontractor tool

Construction retention calculator for UK subcontractors

Work out the retention amount on a construction subcontract, see how an agreed release might be split and estimate how much is still held. Useful for plastering, rendering, dry lining, screeding and other specialist trade packages.

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Calculate retention

Use the values in your actual subcontract. The default numbers are an illustrative example, not typical or recommended contract terms.

Contract value used for retention (£)Enter the amount to which the agreed retention clause applies. Confirm whether VAT and variations are included.Retention rate (%)Illustrative first release of retained amount (%)Only use a 50/50 split if that is what your contract provides. This setting does not establish a due date.Retention already released to you (£)Enter only retention money actually received, not ordinary invoice payments.

Your estimated figures

Total retained at 5%

£2,500.00

Illustrative first release: £1,250.00
Illustrative later release: £1,250.00
Retention already paid: £0.00
Estimated retention still held: £2,500.00

Figures are an arithmetic illustration, not a valuation, payment certificate, VAT calculation or determination of what is legally due. Check your agreed terms, deductions and application dates.

How retention can affect a subcontractor's cash flow

Imagine a plastering subcontract with an agreed value of £50,000 and a retention rate of 5%. The total retained amount would be £2,500. If the written contract provides for half of that retention to be released at one milestone and the balance at another, those illustrative amounts would be £1,250 each. The actual release events and dates must come from the contract.

Check what the percentage applies to

Identify the contract value, any agreed variations and the rules for retention on each payment application.

Keep the evidence

Keep valuations, accepted variations, invoices, completion records and payment correspondence against the job.

Track what was actually received

Record retention held and released separately from ordinary invoice payments, then reconcile against the contract.

Retention calculator questions

How do I calculate retention on a subcontract?

Multiply the agreed value used for the retention calculation by the retention percentage stated in your subcontract. For example, £50,000 × 5% = £2,500. Your contract determines the amount to which retention applies, including any treatment of variations and VAT.

When is construction retention released in the UK?

The release dates and amounts depend on the terms of your contract and the relevant project events. Some agreements release a portion on practical completion and the remainder following a defects period. This calculator illustrates an allocation; it does not determine when payment is legally due.

Can I calculate retention on variations?

Check the written subcontract and agreed variation terms. Add variations to the contract amount only where they form part of the value on which retention is calculated. Keep the agreed change and supporting evidence with the project.

Does the calculator save my customer or project details?

No. The free calculator runs in this page and does not save the figures to a SubCon account. To keep retention figures, variations and invoices with a live project, explore the SubCon job management software.

The app to get you paid

A free calculation is useful. Keeping the whole job's payment record together is better.

SubCon Systems connects quotations, variations, invoices and retention records with the project. Keep track of commercial changes rather than losing the details in separate files.

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