Affidavi / Lien calculator

Ontario construction lien deadline calculator

Construction Act, RSO 1990, c C.30 — ss. 31, 36(2), 37(1) · Free, runs in your browser, nothing is sent anywhere

Three deadlines kill lien rights outright: the lien must be preserved within 60 days of its trigger (s. 31), perfected within 90 days after the last day it could have been preserved (s. 36(2)), and the perfected lien's action must be set down for trial within two years of its commencement (s. 37(1)). Enter the dates you know; the calculator computes the deadlines conservatively — from the earliest trigger you enter — so it can ring early, never late.

Your dates

Enter any you know — the earliest entered trigger governs the computation. All fields optional.

Last supply of services or materials

Publication of the certificate of substantial performance (s. 32)

Completion of the contract

Abandonment of the contract

Termination of the contract (s. 31 notice)

Certification of the subcontract (s. 33)

Lien action commenced (for the set-down clock)

Calculated from the dates you entered — verify every date against the Act and your facts before relying on it.

Why "conservative"? Section 31 branches by role (contractor vs. subcontractor) and by whether supply predates substantial performance. Rather than ask you to self-classify — and risk a late answer — this calculator takes the earliest trigger date you enter and runs the 60-day clock from it. When your entered dates include the governing trigger, the computed deadline is never later than the true one. A deadline that can only ring early is the safe kind; a calculator that guesses your role is not.

The three clocks, in plain terms

Preserve — 60 days (s. 31). Register the claim for lien against title (or, where the lien does not attach, give it to the owner) within 60 days of the trigger: publication of the certificate of substantial performance, last supply, completion, abandonment or termination.
Perfect — 90 more days (s. 36(2)). A preserved lien expires unless perfected — action commenced and certificate of action registered — within 90 days after the last day preservation was possible (i.e. trigger + 150 days).
Set down — 2 years (s. 37(1)). A perfected lien expires on the second anniversary of the commencement of the action unless it is set down for trial or an order/judgment intervenes.

The January 2026 amendment wave (annual holdback release) changed holdback mechanics — not these preservation, perfection and expiry milestones.

The clock is one card of the construction lien kit.

Affidavi drafts the claim for lien, written notice, lien-action statement of claim, certificate and discharge forms — with this deadline clock on the matter, computed the same conservative way. On your computer, never uploaded. Launching soon with a 14-day free trial.

See pricing & get notified

Sources: Construction Act, RSO 1990, c C.30 (ss. 31, 36, 37) · See also: the guides hub

This calculator is general information, not legal advice, and its conservative collapse is not a substitute for the Act's actual branches. Lien deadlines are unforgiving — confirm dates with counsel before relying on them.