A flyer sent out to residents of the Leeds North East constituency by the party's candidate Jon Hannah informed voters that the 2017 general election would be taking place on November 8, rather than the confirmed date of June 8.
Party agents had clearly noticed the error, as the mistake had been covered by a black sticker.
A woman living in the Potternewton Park area of the constituency posted a photo of the gaffe hidden behind the sticker.
Mr Hannah, of Chapel Allerton, admitted that his party had decided not to spend money on a second print run of the leaflets.
"'When we noticed that an error had been made on our leaflet we made a decision to correct it by obscuring it with a hard-to-remove sticker. This decision was made as we are a small local party who rely on donations from our members, rather than big business or unions, to fund our campaign we believe this was a more cost effective and greener solution than disposing of them and purchasing new ones."
The seat is currently held by Labour's long-serving Fabian Hamilton, but is being targeted by the Conservatives due to the shifting demographics of the area.