Most contracting firms that buy a general ERP end up in the same position: the system holds the ledger and the stores, while certificates, retention and subcontractor positions live in parallel spreadsheets. The cause is not a weak system — it is that construction's core document does not exist in it.
Why general systems break here
In trading, the revenue document is an invoice: items, quantities, prices. In construction it is an interim payment certificate, and its structure is entirely different:
- Work executed, measured against BOQ lines each carrying a contract quantity and a cumulative executed quantity.
- Materials delivered to site but not yet installed, valued at a percentage.
- Less retention, a percentage of the work value, normally released in two stages.
- Less advance recovery, a percentage of each certificate until the advance is fully recovered.
- Plus variation orders that may add lines outside the original BOQ.
Because that structure is unsupported, the certificate gets represented as a simplified invoice plus manual journals. The link to the BOQ lines is lost, so the system no longer knows the remaining quantity per line, the retention balance due for release, or how much of the advance has been recovered.
The cycle as the system handles it
Tender and pricing
A tender is built on a bill of quantities, and each line is priced through a rate analysis covering materials, labour, equipment and indirect cost. That analysis remains the reference for comparing actual against estimated cost at line level, not just at project level.
Contract and BOQ
On award, pricing becomes a contract with an approved BOQ and agreed retention, advance and tax percentages. Variation orders are added later as lines linked to the same contract, with their effect on total value tracked.
Interim certificates
A certificate is raised with cumulative executed quantities; the system derives the movement since the previous certificate, applies retention, advance recovery and tax, and generates the accounting entry — contract revenue, retention receivable, advance recovery and the client debt.
Subcontractors
A subcontractor has a contract, BOQ, certificates, retention and an advance — the same logic mirrored. This answers the question contractors actually care about: how much have I certified to the client on this line, and how much have I paid the subcontractor for it?
Guarantees and post-dated cheques
Tender, performance and advance guarantees are tracked with expiry and renewal dates and bank margin coverage, with alerts before expiry. Post-dated cheques issued and received are managed with their due dates and cash-flow effect.
Cost control — where margin is won or lost
Contractor profitability does not appear at the end of a project; it leaks during it. Costs are therefore charged to the project from their source:
| Cost source | How it reaches the project |
|---|---|
| Materials | Issued from the site store against a project cost line |
| Labour | From payroll, with site labour distributed to projects rather than to general admin expense |
| Equipment | Operating hours charged to the project at the equipment's cost rate |
| Subcontractors | From approved subcontractor certificates |
| Direct expenses | From purchase invoices charged to the project |
Set against certified revenue, this shows the margin actually realised versus the estimated budget — during the project, not in an end-of-year estimate.
Three editions
A contractor running two projects does not need what a multi-country portfolio needs, but should not have to replace the system on growing. The product ships as three editions from one codebase and one database:
- Lite — project, BOQ, certificates, retention and collection with core books.
- Professional — adds subcontractors, procurement, site stores, equipment and cost control.
- Enterprise — adds multi-company and multi-branch, quality and safety, document management and advanced approval workflow.
Moving between editions enables features; it is not a re-implementation or a data migration.