Main contractors, for their part, must verify what has genuinely been completed before releasing money, and they carry the risk if they pay too early. Retention adds another layer. Handled well, the process keeps work moving and relationships intact. Handled badly, it turns into a monthly argument.
Where certificates go wrong
Progress claims that don't match site reality. A claim submitted as a percentage of a trade package, with no link to measured quantities, invites challenge and delay.
Unclear basis of measurement. If the contract does not make clear how work is measured and valued, every claim becomes a negotiation.
Variations missing from the claim. Approved variations that are not reflected in the certificate lead to under-payment, while unapproved ones lead to disputes.
Slow review cycles. Certificates that sit waiting for a quantity surveyor, a site engineer and a commercial manager to review in sequence push payment past the agreed date.
Manual calculations and spreadsheets. Previous certificates, retention, advance recovery and back-charges are easy to mis-handle in a spreadsheet, and one error carries through every later certificate.
No audit trail. When a figure is questioned months later, nobody can show who changed it or why.
A cleaner certification process
Anchor claims to the BOQ. Each subcontractor claim should reference bill items and quantities, so the valuation is a comparison of measured progress against the agreed scope, not a lump percentage.
Link progress to site records. Daily reports, inspections and approved work records provide evidence for what has been done and make verification faster.
Include variations automatically. Approved variation orders should flow into the running subcontract value and appear in the certificate without retyping.
Set review steps and deadlines. Define who reviews what, in what order, and by when, with reminders and escalation when a certificate is at risk of missing its payment date.
Calculate deductions consistently. Retention, advance payment recovery, back-charges and previous payments should be calculated by the system, not re-built each month.
Keep a clear history. Every version of a certificate, every comment and every approval should be recorded.
Retention without friction
Retention is typically held as a percentage of each certificate and released in stages, often partly at practical completion and the balance after the defects liability period. Terms vary by contract and should be confirmed in the agreement and applicable law.
Common problems include forgotten release dates, disputes over whether defects are resolved, and subcontractors who feel their money is held indefinitely. Good practice is to track every retention balance by subcontractor and package, diarise release milestones, and link release to the closure of snags and the receipt of handover documents. When release conditions are visible to both sides, the conversation is about facts rather than goodwill.
Where bonds or retention guarantees are used in place of cash retention, record them with expiry dates so they are renewed or released on time.
Protect cash flow on both sides
Fast, accurate certification is not only a courtesy to subcontractors. It reduces the risk of work slowing down, claims for interest or suspension, and the loss of good trades to a competitor who pays more reliably. For the main contractor, a clear audit trail protects against overpayment and supports the client's own interim payment applications.
Why choose BuildFlow
BuildFlow's commercial module ties subcontractor claims to the BOQ and approved variations, calculates retention, advance recovery and back-charges automatically, and routes each certificate through defined approvals with deadlines and a full audit trail. Retention balances and release milestones are tracked by package, so cash flow and obligations stay visible on one screen.
BuildFlow is a construction and fitout management system built to make certification accurate, fast and defensible.
