A down payment is the amount of cash you pay upfront toward the purchase of a home. It's often expressed as a percentage of the selling price of a home—typically 5–20% depending on the type of loan. The difference between your down payment and the price of the home is what you finance with a mortgage. Generally, if you put less than 20% "down" on a home, private mortgage insurance (PMI) is required in addition to your monthly payment.