How do you find out if a loan is assumable?

Look to the loan agreement to determine if it is assumable by someone else. Then talk to the lender about specific requirements based on the value of the home.
Assumable loans permit one borrower to take over a loan from another borrower without any change in the loan terms. Such loans still exist but they aren't very common or popular (for buyers) in a low-interest-rate environment. Plus, today new assumable loans are almost always adjustable rate mortgages.