Quote from @Eyal Goren:
I read that every mortgage has a Due on Sale clause, which means you have to notify the lender when you sale the property and pay the entirety of the loan when you sell the property.
How do people work with the clause and make these kinds of deals?
First, let's be very clear here.
The mortgage your speaking of is a private agreement between the seller and the lender. The "due on sale" clause (DoSC) obligates the seller to notify the lender if the property is sold.
Failing to do so would place the seller in violation of this agreement, giving the lender the right to accelerate the loan.
But no laws are being broken here.
So, subto is neither legal nor illegal.
Second, it only works because most lenders are more interested in receiving payments than in invoking the DoSC clause and foreclosing on the property.
But, it can work, provided seller and buyer are both on board and the proper process is followed.