Family First is vowing to fight a move to have it de-registered as a charity.

The Charities Board has sent it notification of de-registration, despite the advocacy group successfully seeing off the same move last year.

Family First's National Director Bob McCoskrie says the group will again defend its status in court, but if it loses, a lot of other groups should be worried.

He says the move won't stop their advocacy work, but it will cost it tax breaks.