Firefighters say they are not surprised, but are disappointed their employer is appealing a decision giving them a day off in lieu if they work on a public holiday.

Last month the Employment Court ruled the new Holidays Act means firefighters are entitled to the day off.

The Fire Service is now taking the matter to the Appeal Court.

Union spokesman Derek Best says firefighters had thought they were in constructive discussions with their employer about how to implement the change.

He says with an appeal hanging over their heads, they will have to re-evaluate the negotiations.

The Fire Service says the change will cost it between $3.5 million and $5.5 million a year.

The Fire Service is now taking the matter to the Appeal Court.

Mr Best says it is concerning workers are having to fight so hard to get what the government had determined they are entitled to.

The Fire Service says the legal issues have implications for other employers.