He had been nominated last week for outstanding guest actor in a comedy for his role as Jeff Kane in the HBO show.
The category is open to actors who have appeared in less than 50% of a programme’s current series.
MacNicol appeared in five of the 10 episodes of Veep’s latest season – exactly 50%.
The Television Academy told The Hollywood Reporter: “Upon review of the category, we have determined that Peter MacNicol unfortunately exceeds the number of episodes permissible for inclusion.”
The academy acknowledged MacNicol’s entry had been eligible at the time of submission, but added he had subsequently appeared in a further Veep episode.
“Unfortunately, that additional appearance places him in 50% of the season’s episodes and makes him no longer eligible to compete in the guest actor category,” it said.
“This decision is in no way a diminishment of Mr MacNicol’s stellar performance on this season of Veep.”
The academy said a replacement nominee would be announced shortly.
Veep – a comedy produced for subscription network HBO – has just concluded its fifth season.
The show was conceived by The Thick of It creator Armando Iannucci as a political satire focusing on the fictional US vice president and her staff.