I have two credit cards: a Visa and a Mastercard both from FUSA. Each month I run them up (sometimes easily to $1000+ because I travel so much on business), each month I pay them off (expense checks from my employer are quite prompt). Paying off the total amount when it's over a $1000 apparently triggers an automatic form letter begging you not to leave FUSA and it will give you a wonderfully low interest rate if only you will transfer your debt back to their card. The assumption being made that you have acquired another credit card and have transferred the debt. I ignore these letters and the "convenience checks" included with them. But yesterday I actually got a telephone call from a FUSA rep quite concerned about my large payments and wasn't there any debt, any debt at all that I wanted to transfer to my credit card? Department store, automobile loan anything. I felt almost wicked not having anything to transfer.But after I hung up I got to thinking. I do have a debt. My home mortgage. And by coincidence my principal balance is very close to what my credit card limit is. The 4 month (or it might even been for as long as 6 months) low low rate to entice me back into credit card debt is substantially lower than my mortgage rate...and after the low rate expires the fixed rate is still a smidgen below my mortgage interest.I can't think of anything to keep me from using those "convenience checks" to pay off my mortgage. But there's got to be something wrong here. I inherently don't trust FUSA. But I can't think of a reason not to do this. What am I missing?