There are generally two types of buydowns: a permanent buydown and a temporary buydown.  A permanent buydown lets you pay extra points to get a low interest rate over the life of your loan.

A permanent buydown can be paid by the seller or the builder as an incentive to finalize a sale by creating lower monthly payments. Sellers can also benefit from assisting with a buydown with a difficult to sell property or during slower market conditions.  It increases the buyer’s ability to qualify for a loan, therefore, allowing the home to be sold quicker.  A buydown offer is usually less than a price reduction on the home. 

With a temporary buydown, you prepay interest in exchange for a lower rate during the early years of the loan.  The most common temporary buydown is call the "3-2-1",  meaning the mortgage payment in years one, two and three is calculated at rates 3 percent, 2 percent and 1 percent, respectively, below the rate on the loan.  On a 2-1 buydown, the payment in years one and two is calculated at rates 2 percent and 1 percent below the loan rate.  On a 1-0 buydown, the payment in year one is calculated at 1 percent below the loan rate.

A temporary buydown can be a benefit to a buyer whose current income is low but anticipates that it will increase during the next two years.  First-time homebuyers who need to purchase all of the furnishings that go into a new home may also find a temporary buydown appealing.