The department now says, however, that helmets are back on the list.
The question had MPs going at it today in question period.
The NDP and the Liberals called the oversight an example of mismanagement that would end up costing taxpayers.
The March budget said the government would eliminate tariffs of between 2.5 per cent and 18 per cent on products such as ice skates, hockey equipment, skis and snowboards.
Shelly Glover, parliamentary secretary to Finance Minister Jim Flaherty, insisted several times during question period that hockey helmets would indeed be covered under the tariff cuts.
"It has been brought to our attention that hockey helmets were not included on the list of products receiving tariff relief," the government said in a statement.
"This was an oversight at Finance and they will be eligible for tariff relief going forward."
Still, the error gave opposition critics plenty of ammunition.
"Why are Conservatives raising prices and taxing hockey players' safety equipment?" asked Matthew Dube, a Quebec New Democrat.
"For greater clarity, hockey helmets would be covered under the tariff relief in the budget," an exasperated Glover replied.