Summary

Retention is a holdover from the days when there was no statutory protection for clients against defective workmanship. The principle: a client withholds a small percentage of every payment until they're sure the work is right. If defects appear in the defects liability period, the retention pays for the rectification. If the work is sound, the retention is released. In theory it's fair to both sides — the contractor gets paid for substantively complete work, the client has a fund to draw on if things go wrong.

In practice retention is the single biggest cashflow burden on UK subcontractors and small contractors. A subbie running a £100,000 job at 5% retention loses £5,000 of cashflow for 12+ months. Across multiple contracts, that's the difference between a healthy business and one that can't make payroll. The 2018 Carillion collapse left over £800m in unpaid retentions, kicking off a still-unresolved campaign for retention reform (mandatory deposit accounts, abolition, or 30-day release). As of mid-2026 the law hasn't changed but pressure continues to build.

This article covers retention in JCT and NEC contracts (the two dominant UK construction contract forms), the Construction Act 1996 statutory protections that apply regardless of contract terms, payment notice rules, adjudication, late payment interest, and practical strategies for negotiating retention down or out and chasing release. UK only — covers England and Wales primarily, with notes on Scotland where law differs.

Key Facts

Quick Reference Table

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Contract type Typical retention Typical release
JCT Minor Works 3–5% 50% at PC, 50% at end of 6-month rectification
JCT Standard 3% 50% at PC, 50% at end of 12-month rectification
NEC4 Option A/B + X16 3–5% (negotiable) Per X16 terms; often half at PC, half at defects cert
Small subcontract (informal) 0–10% Often "on final payment"; risky for cashflow
Domestic bespoke (homeowner) 0–10% Often retained until snags cleared; statutory protections reduced
Payment process step (Construction Act) Timing
Payee Application for Payment Per contract (typically monthly)
Due Date Per contract (typically 7 days after application)
Payer's Payment Notice Within 5 days of due date
Pay Less Notice Not less than 7 days before final date for payment
Final Date for Payment Per contract (typically 14–30 days after due date)
Interest accrual begins Day after final date for payment
Late payment penalty (LPCDIA 1998) Statutory remedy
Interest rate 8% + Bank of England base rate
Debt up to £999.99 £40 fixed compensation per invoice
Debt £1,000–£9,999.99 £70 fixed compensation per invoice
Debt £10,000+ £100 fixed compensation per invoice
Recovery costs (reasonable) Can be claimed in addition to fixed compensation

Detailed Guidance

Retention in JCT contracts

JCT (Joint Contracts Tribunal) contracts are the dominant private-sector contract form in the UK. The retention clauses vary slightly by JCT family but follow a consistent pattern.

In JCT Minor Works (MW2016 / MW2024), retention is set in the Contract Particulars — typically 5% (or whatever's agreed). On every interim certificate, the architect/contract administrator deducts the retention percentage from the value of work executed. Half the retention is released on the Certificate of Practical Completion; the other half on the Certificate of Making Good (issued at the end of the rectification period, typically 6 months).

In JCT Standard Building Contract (SBC2016 / SBC2024), retention typically 3%, rectification period 12 months. The principle is the same.

Practical points:

Retention in NEC contracts

NEC4 (the modern engineering and construction contract family, dominant in UK public sector) handles retention under Secondary Option X16. X16 must be expressly included — without it, NEC has no retention.

If X16 is included, the contract data states:

NEC retention is typically released similarly: half at Completion (the NEC equivalent of PC), half at the end of the defects date period.

NEC also offers Option Y(UK)1 — Project Bank Account, which can carry retention from the PBA, isolating funds from main contractor insolvency.

The Construction Act 1996 — what every UK tradesperson should know

The Housing Grants, Construction and Regeneration Act 1996 (amended by the LDEDC Act 2009) is the cornerstone statute for UK construction payments. It applies to all "construction operations" (Section 105 defines this broadly — covering virtually all on-site building work) other than work for residential occupiers in their own home (Section 106 exception).

Key statutory rights, which the contract cannot exclude:

  1. Right to stage payments (s109) — any contract longer than 45 days must allow interim payments
  2. Payment notice / Notified Sum rules (s110A and s110B) — formal notice regime; non-compliance means the payer must pay the sum the payee applied for
  3. Pay Less Notice (s111) — payer must serve formal notice to withhold less than the Notified Sum, no later than the prescribed period before final date for payment
  4. Right to suspend performance (s112) — payee can suspend work (with 7 days written notice) if payment is not made by final date for payment
  5. Prohibition on "pay-when-paid" clauses (s113) — unenforceable, save where the upstream party is insolvent
  6. Right to adjudication (s108) — either party can refer any dispute to an adjudicator at any time, with a decision in 28 days

For residential occupier contracts (homeowner client, work on their own dwelling), most of these statutory rights do NOT apply by default. The contract must contain equivalent provisions or these rights are simply not available. This is why a written, well-drafted contract for domestic work matters — see written contracts tradespeople.

Adjudication — fast remedy for payment disputes

Adjudication is the killer feature of the Construction Act for cashflow. Either party can refer a dispute (typically: I'm not being paid what I'm owed) to an adjudicator at any time. The adjudicator must decide within 28 days (extendable to 42 with the parties' consent). Their decision is binding until the dispute is finally determined by litigation, arbitration or agreement.

In practice, most adjudication decisions are accepted and not relitigated — the costs of litigation make it disproportionate to revisit a £15,000 retention dispute through the courts.

Adjudicator's fee typically £1,500–£5,000 (split between parties or borne by losing party at adjudicator's discretion). Specialist adjudication solicitors charge similar fees. For a £20k+ payment dispute, adjudication is almost always cheaper than letting the cashflow harm continue and far cheaper than litigation.

The ICE, RICS, CIArb, and the Construction Industry Council each maintain panels of trained construction adjudicators.

Late payment interest — statutory and contractual

Under the Late Payment of Commercial Debts (Interest) Act 1998, business-to-business contracts attract statutory interest at 8% + Bank of England base rate from the day after the final date for payment. As of mid-2026 with base rate at (verify current rate, around 4–5%) that's around 12–13% per annum.

Plus statutory fixed compensation per invoice:

Plus reasonable recovery costs (e.g. legal fees) over and above the fixed compensation.

The statutory rate applies UNLESS the contract specifies a "substantial remedy" instead — many JCT and NEC contracts specify their own interest rate. If the contractual rate is genuinely a substantial remedy (typically 5%+ above base), it applies in place of the statutory rate. If it's less than 8% over base, the statutory minimum applies regardless of what the contract says.

For residential occupier contracts (domestic work), LPCDIA does not apply — instead, the County Court interest rate (currently 8% flat) applies post-judgement on any sum claimed and awarded.

Negotiating retention down or out

For subcontractors, getting retention down is often the single biggest cashflow lever. Strategies that work:

  1. Retention bond — offer to provide a bond from a bank or surety company in place of cash retention. Costs you the bond premium (typically 1–2% of bonded amount per annum) but frees the cash.
  2. Cap retention — agree that retention only applies up to a maximum figure (e.g. 3% capped at £15,000), not unlimited
  3. Reduced rate — push for 1.5–3% rather than 5%
  4. Faster release — agree half-release earlier (e.g. at 50% completion instead of PC)
  5. Just refuse — for small jobs (£10k or less) and where you have leverage, decline retention altogether. Many smaller domestic and commercial jobs run with no retention if both sides agree
  6. Cashflow-friendly milestone payments — design payment terms that front-load (mobilisation payment, milestone payments at stages) so the retention is a smaller proportion of your exposed cashflow at any given time

Pursuing overdue retention

Common scenario: PC was 8 months ago, rectification period has ended, snags have been cleared, but the retention release hasn't been paid. Process:

  1. Written demand — formal letter (not email) asking for the half/final retention release with a 14-day deadline
  2. Notice under LPCDIA — claim interest and statutory fixed compensation
  3. Adjudication — refer the dispute to adjudication; this is what the Construction Act exists for
  4. County Court — for residential occupier contracts (where adjudication isn't available), small claims track for sums up to £10k, fast track for up to £25k, multi-track above

Most retention disputes settle once a formal demand or notice of adjudication is served — clients know the cost of fighting and losing is high. Keep records of all communications, dates of practical completion, snag closeout, and the contract terms.

Project Bank Accounts (PBAs) and retention reform campaigns

Project Bank Accounts are ring-fenced accounts (usually held by the client or trustee) from which all tier-1 subcontractors and suppliers are paid directly. PBAs are mandatory on some Crown Commercial Service framework contracts and several Highways England / Network Rail / Transport for London contracts. They reduce retention disputes because funds are protected from upstream insolvency.

The Build UK and Construction Leadership Council have campaigned since 2018 for mandatory retention deposit schemes or abolition. Multiple Private Members' Bills have been introduced (most recently the Construction (Retentions) Bill) but none has become law as of 2026. Stay alert — change may come.

Frequently Asked Questions

Is retention legal on a small domestic job?

Yes, retention is legal on any UK construction contract including domestic work — there's no statutory minimum or maximum percentage. However, the Construction Act statutory payment protections (notably adjudication and payment notices) don't apply by default to residential occupier contracts. If you're a domestic client withholding retention, expect this to be a contract matter only, with County Court rather than adjudication as the remedy. If you're the contractor, a written contract with clear retention release triggers is essential.

Can the client withhold retention longer than the contract states?

No — once the defects liability/rectification period has ended and the Making Good certificate has been issued (or its equivalent), the retention is contractually due. Withholding it beyond that point is a breach of contract. Use the formal payment notice and Pay Less Notice regime to challenge any withholding, or refer to adjudication.

What if the main contractor has gone bust before paying me retention?

This is the worst-case retention scenario. Without a Project Bank Account or retention bond, your retention sits in the main contractor's general bank account and is treated as an unsecured debt in their insolvency. You join the queue of unsecured creditors and typically recover pennies in the pound. The 2018 Carillion collapse exposed this risk — £800m+ of unpaid retentions were effectively wiped out. The argument for PBAs and mandatory retention deposit schemes is exactly this.

Can I add retention interest charges to my invoice in advance?

For commercial work (B2B) yes — many contractors include a clause in their T&Cs stating "interest at [8%/12%] above Bank of England base rate applies to all overdue invoices per the Late Payment of Commercial Debts (Interest) Act 1998." The statutory rate applies as a minimum even without the clause but stating it on every invoice makes the position clear.

How does retention work in Scotland?

Scottish law has slightly different statutes (the Construction Act applies UK-wide, but LPCDIA and County Court remedies differ — the Scottish equivalent is the Sheriff Court and Court of Session). Retention practice in Scottish JCT and NEC contracts is the same. Adjudication is the same statutory right UK-wide. Specific differences are minor for most practical retention disputes.

Regulations & Standards