Mortgage linked Checking Acciunts

[Jonathan Cisneros]

Has anyone heard of a mortgage that has a checking account linked to it and at the end of every bill cycle(like a credit card statement) the mortgage company will check your balance and reduce your principal by what is in your checking account and only charge interest on the delta. Ex. $150,000 loan with $50,000 in your checking account so the mortar company will only charge interest on $100,000 instead of $150,000. The mortgage company doesn't necessarily take the money but more so credit you.

Has anyone heard of this? If so what type mortgage is this called?