BR 384:12(1) :כיון דמטא למכסא‏ : when he arrived at the custom house
See the entire entry for mḵes, maḵsā n.m. duty, i.e., tax on goods

BR 384:12(1) :הב מכסא‏ : give the duty
See the entire entry for mḵes, maḵsā n.m. duty, i.e., tax on goods