<prompt> Translate the following text to EnglishKosa moja la kawaida ni kuhesabu misaada ya shirikisho kama kodi ya serikali na ya mitaa, lakini hiyo ni kuhesabu mara mbili, kwa kuwa tayari zimelipwa na kodi ya shirikisho.  <response>: One common mistake is to count federal grants-in-aid as state and local taxes, but thats double counting, since theyre already paid for by federal taxes. 