An unexpected holiday for ACT Government workers on the Monday after Anzac Day is predicted to cause problems for federal public servants heading to work.

About 20,000 people will get a holiday on April 27, including ACT Government shopfront workers and ACTION bus drivers.

In addition all public schools in Canberra will be closed.

However those employed by the Federal Government or in the private sector in the ACT have a normal work day scheduled.

ACTION buses has announced arrangements to help cope with the regular traffic heading to work despite the ACT Government holiday.

TAMS Minister Shane Rattenbury told 666 ABC Canberra, buses will run on a weekend timetable and the fares will be free.

"With the 200 drivers available what we can offer is a Saturday service and an enhanced rapid bus service, so that's the high frequency buses that run on spine routes," he said.

"What I can't do is guarantee that we can run normal school services because we simply don't have enough drivers.

"It is still four and a half weeks away, so parents need to be clear about that school services won't run on that day."

Chaos for parents and private school students: Opposition

Opposition Leader Jeremy Hanson said the day will be chaotic, particularly for children at private schools who will find it difficult to get a bus.

"Kids are going to be left high and dry. That's pretty clear," he said.

Jeremy Hanson said the lack of school buses would cause chaos for parents of students at private schools. ( ABC News )

"The Government's put on limited bus services and they're saying they're going to be free.

"But there's not much point having a free bus if you can't actually catch it, if it's not coming. So look it's a bit of chaos and it's a lot of disruption for a lot of people."

Mr Rattenbury acknowledged the lack of buses would be a problem and the enterprise agreement which allowed for the holiday would need to be amended in future.

"It comes around once every six or seven years when Anzac Day falls on a Saturday," he said.

"I think people will find this a bit odd, and they will be wondering why as Anzac Day is being acknowledged on the Monday when Saturday is formally the public holiday."

However the union that represents bus drivers said it would make more sense to give every Canberran an extra day off than to scrap the clause in the enterprise agreement.

Klaus Pinkas from the Transport Workers Union said the problem only happens every six or seven years.

"To me the logical solution would be to have it as a public holiday for everybody," he said.

"But individual businesses and individual schools, private schools make up their own mind whether they're open that day or not."

This year's Anzac Day commemorations on April 25 will mark 100 years since the landing at Gallipoli by Australian and New Zealand troops.

The ACT Government joins Western Australia as being the only two jurisdictions having an additional holiday on April 27.