I am doing an empirical test of the CIP from the recent financial crisis between Canada and the United States. I am using 1,2,3,6,12 month forwards (monthly data). What interest rates should I use? I don't think T-bills are suitable because you can lend at that rate, but not borrow. Currently I am using LIBOR rates for the US and Canada (even though the Canadian LIBOR was discontinued in 2013 I think it is sufficient). Any feedback would be appreciated.