The Revenue Commissioners have lost a High Court appeal against a decision of the Language Commissioner over information distributed to the general public about the Local Property Tax between 2012 and 2013.

It is the first appeal of its kind against the Language Commissioner.

An information booklet about the tax was delivered to 1.6m households, but an Irish language version was distributed to only a few thousand homes.

The Language Commissioner undertook an investigation, having received a number of complaints from the public.

The commissioner decided that Revenue had breached Article 9.3 of the Official Languages Act, under which public bodies are obliged to communicate with the public in general bilingually or in Irish only.

Revenue did not accept the decision and appealed against it.

It argued that this was not a case of "communication with the public in general" because each information booklet was included, with a letter, in an envelope.

It argued that the envelopes were addressed to particular families or individuals at particular postal addresses.

The appeal was heard last November.

Judge Colm Mac Eochaidh today ruled that the Revenue's argument could not be accepted.

If it were, he said, it would mean that obligations under the Official Languages Act could always be avoided simply by placing information or communications in envelopes.

This, he said, was not in keeping with the spirit of the legislation as passed by the Houses of the Oireachtas.

Revenue now has three weeks to appeal the decision.

A decision on costs will be made next Friday.

Language Commissioner Rónán Ó Domhnaill welcomed the decision, saying it clarified the obligations involved when dealing with the public.