Progress claim & retention calculator
Work out exactly what a progress claim pays after retention and GST — so the invoice you send is right the first time.
Use the calculator ↓Work out a progress claim
Retention is often capped (commonly 5% of the contract, released on practical completion). GST applies to the amount after retention here — confirm the treatment in your contract.
How builders use this
Invoice with confidence
Turn a percentage of the contract into the exact figure payable this claim, retention and GST included.
Track retention
See the retention held on each claim so you know what is owed back to you at completion.
Avoid disputes
A clear, correct claim keeps cashflow moving and keeps the builder–client relationship out of the weeds.
How progress claims and retention work
On most building contracts you invoice in stages as the work progresses, rather than in one lump at the end. Each progress claim covers the value of work completed since the last claim — here, expressed as a percentage of the total contract value.
Retention is a portion the client withholds from each payment as security that the job will be finished and defects made good. It is commonly around 5% and is often capped at a percentage of the whole contract, with half released at practical completion and the balance at the end of the defects period. This calculator withholds your retention percentage from the claim and adds GST to the remainder.
Contracts differ on whether GST applies before or after retention and on how retention is capped and released, so always read the specific payment terms of your contract.
Frequently asked questions
What is retention on a building contract?
It is money the client holds back from each progress payment as security that the work will be completed and defects fixed. It is usually released in two parts — at practical completion and after the defects liability period.
Is retention taken before or after GST?
It depends on the contract. This calculator withholds retention from the claim value and then adds GST to the balance, but some contracts calculate it differently — always follow your contract’s payment schedule.
Is there a cap on retention?
Commonly yes — retention is often capped at a set percentage of the total contract value (for example 5%), so it stops accruing once that cap is reached. Check your contract for the exact terms.
Get The Builder Times in your inbox
The week's essential builders’ reading — free, no noise, unsubscribe any time.
This calculator is a general guide for building progress claims and is not legal or accounting advice. Retention and GST treatment depend on your contract — confirm the terms before invoicing.