Is your home listed on the MLS with a buyers commission listed already? If it is the commissions are paid through escrow when the house closes. If you are not offering a buyers commission the buyers agent will present you with a commission addendum and once signed by all parties the buyers offer would be presented to you. That would be turned in to escrow and paid when the house closes. Lastly you do not pay any commissions and the buyer pays his agent to represent them. Once again it is paid through escrow. If you are not paying commission the buyers offer may or may not be adjusted to cover their cost.