tax certificate

from The Collaborative International Dictionary of English v.0.48

Tax certificate \Tax certificate\ (Law)
   The certificate issued to the purchaser of land at a tax sale
   certifying to the sale and the payment of the consideration
   thereof, and entitling the purchaser upon certain conditions
   and at a certain time thereafter to a deed or instrument of
   conveyance (called a tax deed) of the land, to be executed by
   the proper officer.
   [Webster 1913 Suppl.]