BC州では賃貸住宅には Residential Tenancy Act という法律があり、デポジットを要求する場合は、家賃の半月以内でなければならないという規定があります。
http://www.tenants.bc.ca/tsg1/index.htmlここに賃貸契約に関することが載っています。デポジットに関しては、3章の「Deposit」を参照してください。
以下が抜書きですが、半月以上払ってしまっていた場合は、この法律によれば、次の家賃の支払い時に、払い過ぎた分を相殺するようにと書かれています。
Security Deposit(Damage Deposit)
A landlord can ask you for a security deposit (also called a damage deposit) to cover the costs of damage or unpaid rent. Your landlord can only ask for a security deposit when you first agree to rent the place. You have to pay the full security deposit within 30 days after you move in or you can be evicted.
A landlord can only charge you half a month’s rent for a security deposit. This includes all deposits for things that come with the rent. Your landlord can’t ask you to pay extra deposit money for things like keys or pets. If you pay cash, get a receipt. The law doesn’t make your landlord give you a receipt. It is better to pay with a cheque or money order.
If you pay more than half a month’s rent for a deposit, the law says you can take the extra amount off a future rent cheque. You don’t have to go to arbitration. But you should write a letter to your landlord saying why you’re not paying the full rent. Keep a copy of your letter.