A 2-1 buydown provides for a reduced interest rate for the first two years:

Year 1: Note rate minus 2% (6% - 2% = 4%)

Year 2: Note rate minus 1% (6% - 1% = 5%)

Years 3–30: Note rate (6%)

“In a 2-1 buydown, the interest rate is reduced by 2% the first year and 1% the second year. The third and subsequent years, the rate is the note rate.”

— SAFE MLO National Test Study Guide; CFPB Mortgage Glossary