Powayseller is right. At any given time mortgage rates would be higher than the TBill returns.
But if you are speculating on the interest rates to rise and lock in a fixed rate mortgage; in certain Tax situations you could use the spread to advantage. But there is always interest rate risk.
I have’nt done that on a mortgage, but on my car purchase. I had a low interest offer and at that time returns on low risk CDs and TBills were lower than the interest. Although I could have easily paid off the loan then, I took the interest hit and am now getting good returns on the loan amount. But if the interest rates had stayed in the bottom, I would have been losing money on all the interest payments.
