Employment standards · Labour relations
Union open period calculator.
While a collective agreement is in force, a rival union can only apply to take over the bargaining unit, and employees can only apply to remove the union, in narrow windows. Enter the agreement start and term to see when those windows fall, federally or in British Columbia.
Federally the window is the last 3 months of an agreement of 3 years or less; for a longer agreement it is months 34 to 36, the 3 months before each later anniversary, and the last 3 months (Canada Labour Code s.24(2), and s.38(2)(a) for revocation). In British Columbia a rival application is open in months 7 and 8 of the last year (of the third year and each year after, for agreements over 3 years), or July and August each year in construction (s.19).
Your collective agreement
Open windows
Enter a start date and term and press Calculate.
What this does and does not cover
This calculator only works out calendar windows from the start date and term you enter. It does not decide whether an application will succeed, and it does not count signatures or membership. Applications also have evidence and form requirements set by the labour board. Confirm with the board or a labour lawyer before relying on a date.
Federal rules
Canada Labour Code s.24(2)(c): where an agreement of not more than three years is in force, a certification application may be made only after the start of the last three months of its operation. Under s.24(2)(d), for an agreement of more than three years, only from the start of month 34 up to before month 37, then in the three months before the end of each later year, and in the last three months. Under s.38(2)(a), employees may apply to revoke certification while an agreement is in force only during those same s.24 periods, unless the Board consents. With no agreement in force, s.24(2)(b) and s.38(2)(b) look to 12 months from certification. Under s.24(3) and s.38(5), neither application may be made during a strike or lockout that is not prohibited by the Code, except with the Board's consent.
British Columbia rules
Labour Relations Code s.19(1): for an agreement of 3 years or less, a union may apply in the seventh and eighth months of the last year; for a longer agreement, in the seventh and eighth months of the third year and each year after. Under s.19(2), in construction the window is July and August of each year. Under s.19(2.1), no application within 22 months of an earlier application that the Board decided on the merits. Under s.19(3), not during a strike or lockout without the Board's consent.
Decertification is separate: s.33(2) requires at least 45% of the employees in the unit to sign the application, and s.33(3)(a) bars it during the 12 months immediately after certification (also 12 months after a refused cancellation). The text of s.33(2)-(3) as read ties no BC decertification window to the agreement dates, so this tool shows only the 12-month bar.
Assumptions in the arithmetic
Month 1 starts on the agreement start date and months are whole calendar months (a start on the 31st clamps to each month's last day). The BC “last year” is the final 12 months counted back from the end of the term. Continuations past the term are not projected. If your agreement is shorter than 12 months, the whole agreement is treated as the last year. Confirm how the board would count your dates.
Sources, read 29 September 2026: Canada Labour Code s.24, s.38 and the BC Labour Relations Code, RSBC 1996 c.244 (s.18, 19, 33). Ontario is not covered because the Labour Relations Act text could not be read.
Frequently asked questions
What is an open period?
The stretch of a collective agreement during which a rival union may apply to be certified, and employees may apply to have the current union removed. Outside it, those applications are generally barred.
How do I decertify a union?
Federally, an employee claiming to represent a majority applies to the Canada Industrial Relations Board, and only during a s.24 window while an agreement is in force. In BC, at least 45% of the employees in the unit must sign an application, and not within 12 months of certification. Get advice on the evidence and form the board requires.
Does a strike or lockout change the window?
Yes. Federally and in BC, these applications cannot be made during a strike or lockout without the board's consent.
Why is Ontario missing?
The Ontario Labour Relations Act windows could not be verified against the statute text, so they are left out rather than guessed.
Not legal advice
This is general date arithmetic, not legal advice, and it cannot confirm an application is timely or will succeed. This runs entirely in your browser: nothing you enter is transmitted, stored, or logged.