In short: The defect liability period is the stretch after completion — commonly twelve months, though your contract decides — during which you must make good defects in your own work at your own cost. It does not give the client free extra work, and it does not cover normal wear or damage caused by use. What it does do is hold your money: the balance of retention and often the validity of your guarantee run to the same date, which makes the recorded completion date and a clean written release the two things worth chasing.

The last load leaves site, the final bill goes in, and everybody moves to the next job. Months later a call arrives about settlement along an embankment, and the file that could have answered it is in a box somewhere.

That gap between finishing the work and being finished with the contract is the defect liability period, and it is where a profitable job quietly turns into an argument.

What the defect liability period actually obliges

The obligation is narrow, and reading it narrowly is in your interest.

You are required to rectify defects in the work you executed — things that were not done to the specification, or that have failed because of your workmanship or your materials. The client notifies the defect within the period, you make it good at your own cost, and the matter closes.

What the clause does not do is turn you into a maintenance contractor. Ordinary wear from use, damage caused by how the asset has been operated, and failures flowing from a design or a material the client specified sit outside it. Neither does the period give the client a route to raise items it accepted at completion without recording them.

Where owners lose ground is not on the principle. It is that they argue the principle late, from memory, against a written inspection note the client made at the time.

When the clock starts, and why the date is worth fighting for

The period runs from completion. Which means the recorded date of completion decides your exposure, and a date recorded loosely can cost you months.

Get the completion recorded properly — the certificate, the date on it, and the position on any items still outstanding. If the client is slow to issue it, write and ask, and keep the correspondence. Owners who let the certificate drift often discover that the client is treating a much later date as completion, which pushes the release of their money out by the same distance.

Then diarise the expiry the same day. That single diary entry is what lets you ask for release on time instead of noticing eight months late.

What the period is holding

What is held Typical treatment Released when
Retention deducted from running bills Often part at completion, balance after the period Period expires with no unresolved defect
Performance guarantee Validity commonly extended to cover the period On written release, then returned to the bank
Final bill May be passed but with the balance withheld Per the payment clause, after the period

This is the part owners feel. The work is done and the money is not, because the contract is deliberately holding a sum against the possibility of a defect. Our note on payment delays on government work covers the retention cycle in more detail, and the performance bank guarantee piece covers what a guarantee kept alive for another year costs you in commission and margin money.

Both of those costs belong in your bid. A job whose retention sits with the client for a year after completion is not the same job as one that pays out on the final bill, even at the same rate.

Earthwork has a particular problem

For owners whose work is excavation, filling and compaction, the defect liability period tends to be about one thing: settlement.

Fill placed in the dry behaves differently after a monsoon. An embankment settles, a compacted platform develops a dip, a trench reinstatement sinks below the road surface. The client sees a defect in your work; you may be looking at a consequence of the material specified, the layer thickness directed, or a drainage arrangement that was never yours.

The way to be in a position to say so is set months earlier, on site. Keep the compaction test results and the levels, keep the instruction that told you which material and what layer thickness to use, and keep the joint record of what was measured and accepted. If you record quantities properly for billing, as our pieces on star rates for extra items and delay damages both describe, you already have most of this file.

Handling a defect notice

A notice arrives. Four steps, in order, and none of them is expensive.

Attend, and attend jointly. Inspect with the client’s representative rather than sending someone to look on their own. What is recorded at that inspection tends to become the accepted version of events.

Write your view at the time. If you believe the defect is from use, from design or from a specified material, say so in writing then. A position taken at the inspection carries weight; the same position taken after a deduction reads as an excuse.

Do the work if it is yours. Where the defect is genuinely your workmanship, rectifying quickly is almost always cheaper than the alternative, which is the client having it done elsewhere and recovering the cost from money it is already holding.

Close it on paper. Get written confirmation that the defect is made good, and at expiry ask for written release of the retention balance and the guarantee.

The bottom line

The defect liability period is a narrow obligation with a wide financial reach. It asks you to fix your own defective work; it holds your retention and your guarantee while it runs; and almost every dispute inside it is settled by whichever party has the contemporaneous record.

Record the completion date, diarise the expiry, keep the test results and instructions, and answer notices in writing at the time. If you are pricing the next job, put the cost of money held for a year into the rate — and check current work on the tender opportunities listing before you commit machines that will be tied to the same client for longer than the job itself.

Last updated: 28 August 2026. Rates, schemes, specifications and prices change — confirm current terms with the OEM, dealer, bank or insurer before deciding. Defect liability lengths, release terms and notice procedures are set by each contract; confirm the clause that binds you in your own signed agreement.