If a mortgage includes a clause allowing the lender to require full payment upon default, what type of clause is this?

The clause that allows a lender to require full payment upon default is known as an acceleration clause. This type of clause provides the lender with the right to demand the entire balance of the loan be paid immediately if the borrower defaults on any part of the loan agreement, such as failing to make timely monthly payments.

The purpose of the acceleration clause is to protect the lender's interests by allowing them to recoup their funds quickly if the borrower breaches the mortgage contract. This mechanism also serves as a deterrent against default since borrowers are aware that failing to meet their obligations could result in the immediate demand for full repayment.

The other types of clauses mentioned serve different functions. A prepayment clause pertains to the borrower's ability to pay off the loan in full before the scheduled maturity date, often with or without penalties. A default clause may refer more generally to the terms under which a borrower is considered to be in default, rather than specifically outlining the consequences of default. Lastly, a term clause typically defines the length and conditions of the loan itself, rather than addressing the consequences of a default situation.