In this guide 6 sections
An RA bill claims payment for work done so far, while retention holds back a share of each payment until a later milestone. A variation order changes scope or quantity after award, and each of the three is recorded against the bill of quantities, line by line, so nothing is paid twice.
The bill of quantities is the anchor
The BOQ lists every item of work with a description, unit, quantity and rate, measuring excavation in cubic metres, brickwork in square metres and conduit in running metres. Every line carries a code. Each bill must quote that code.
Everything else hangs off those lines. A bill claims quantities against them, a variation adds or alters them, and retention is calculated on whatever the client’s engineer certifies from the bill.
Hidden rows and merged cells will hurt. Keep one item per row and one code per item, then lock the original contract quantities so that revisions appear as separate columns beside them. Clean it before the first bill.
How a running account bill works
An RA bill is a progress claim. The site engineer measures work done since the last bill, enters quantities in a measurement sheet, applies contract rates, then subtracts earlier claims so nothing is paid twice.
The client’s engineer checks and certifies, and the certified amount often lands below the claim, so the shortfall becomes a dispute that drags through the next three bills.
Number bills in sequence. A cumulative column beside the current quantity, carried forward from the previous bill, catches most arithmetic slips before the client’s quantity surveyor finds them. File scans by bill number.
- Item code and description from the BOQ
- Contract quantity and rate
- Quantity up to the previous bill
- Quantity this bill, from the measurement book
- Cumulative quantity and certified amount
What retention is and when it comes back
Retention is money held back from each payment as security that the work will be finished and that defects will be fixed once the building is occupied. The contract fixes the rate. It also names release points.
Release usually comes in two parts. One portion is paid at practical completion, and the balance follows once the defects liability period ends and the client signs off the final account.
Retention gets lost. It sits on a ledger line for a year, nobody diarises the release date, and the claim finally goes in months late with no chaser from anyone. Put the date in the calendar today.
- Retention held per bill and running total per contract
- Release date for the first portion
- End date of the defects liability period
- Any bank bond offered in place of cash retention
Variation orders change the contract, so record them separately
A variation order is a written instruction that adds, removes or changes work, such as a new floor tile from the client or a partition moved ten centimetres. Both change the quantities.
Keep variations out of BOQ lines. Give each its own number, its own rate basis and its own status, because draft, submitted, approved and rejected are four different positions for the same change.
Early work is the trap. If an instruction was verbal, send written confirmation the same day to whoever gave it, with a measured quantity and a dated photograph of the finished area. Log each instruction. Note who gave it, on which date and in what words, because that record protects you when the final account is argued over a year later.
Keeping all three straight in practice
A register per contract works well. It holds BOQ lines, bills raised, retention held and every variation with its status, so one page tells you where the contract stands today. Software links them, so an approved variation drops its lines into the next bill and retention updates when a bill is certified.
Match bills to receipts monthly. Chase every unmatched item with an owner and a due day written beside it, so unpaid certificates are followed up while the site team still remembers the measurements.
Open your latest RA bill and ask whether you can trace every quantity back to a dated, signed page in the measurement book. If not, repair that trail first. Repeat for retention and variations.
Contract billing register
A one-page register kept for each contract. The top block records client, contract value, retention rate and release terms. Below it, one table lists RA bill number, date, gross claim, certified amount, retention held and payment received, one row for every bill raised so far. A second table tracks variations.
Open a blank worksheet to printQuestions owners ask
What is the difference between an RA bill and a final bill?
An RA bill claims progress during the job, while the final bill closes the account after completion, reconciles every approved variation, deducts earlier payments and requests the retention balance. It is the last bill.
Can a client refuse a variation order?
Yes. A client can refuse any variation that lacks written approval, and refused work may go unpaid, so record the instruction and send confirmation the same day.
Is retention the same as an advance?
No. An advance is paid early. Retention is withheld from each certified bill and paid to you only after practical completion, or after the defects liability period for the balance, once the client signs off.
Where do measurements belong?
In a signed measurement book. Item codes must match the BOQ, so each bill line points back to dated, countersigned pages that the client’s engineer has already seen. Keep the book on site.