Impost From Wikipedia the free encyclopedia Look up impost in Wiktionary, the free dictionary. Impost may mean: A type of tax, especially a tax levied on imports A handicap (usually a lead weight) used in horse racing Impost (architecture): a block or capital on which an arch rests Topics referred to by the same term This disambiguation page lists articles associated with the title Impost.If an internal link led you here, you may wish to change the link to point directly to the intended article.