Consult with the other party to the purchase agreement regarding what changes you wish to make to the original agreement. Draft the language that you plan to add or change in the agreement, or decide what language you will be deleting.
Title the new document "Amendment to Purchase Agreement." Begin the document by stating who the parties are to the agreement and referencing the original agreement, including the date of the original agreement.
State specifically in the body of the amended agreement exactly how the parties want to amend the original agreement. For example, "Paragraph Two shall be amended to read 'the purchase price shall be paid in three equal installments' as agreed by the parties."
Create signature lines for all parties involved. Have each party sign the amended purchase agreement in front of a notary public.
Attach the original purchase agreement to the amended purchase agreement so that it is incorporated into the new agreement.
- business man shaking hands in agreement image by Jorge Casais from Fotolia.com