B.C. residents making prepayments on items they'll receive after July, 2010 will have to add a little extra to the bottom line.

B.C.'s finance minister says the harmonized sales tax -- combining the seven per cent provincial tax with the five per cent goods and services tax -- will be applied to all prepayments made on, or after, May 1, 2010.

The May date is included in transitional rules announced Thursday by Finance Minister Colin Hansen in preparation for B.C.'s July 1 adoption of the 12-per-cent HST.

Transitional rules explain how the HST and provincial tax apply to transactions straddling July 1, and also outline which prepaid items won't be immediately covered by the harmonized levy.

Newspaper and magazine and periodical subscriptions paid before July 1 will be exempt until the next payment, and round-trip tickets on travel started before July are also HST-free.