Do I Have to Repay the First Time Home Buyers' Exemption in BC if I Don't Move In?

This answer covers the law of British Columbia.

Not moving in puts your exemption at risk, because the first time home buyers' exemption depends on you living in the home. You must move in within 92 days of the registration date and continuously occupy it as your principal residence until the first anniversary of registration. The home must also be used only as your principal residence.

A person who moves out before the first year may keep only part of the exemption. The official guidance does not set out how that is calculated, so avoid guessing at a figure. Instead, contact the program at 1-888-841-0090 or PTTENQ@gov.bc.ca. Some events do not disqualify a claim, including the owner's death or a transfer under a separation agreement or Family Law Act court order before the first anniversary.

Be accurate in what you declare. A false declaration that you've never owned a principal residence or never received the exemption leads to a penalty equal to the exemption or refund claimed, on top of that amount. If your plans have changed, a lawyer can confirm how the rules apply to your situation before you act.