UK firms including Ashurst, Norton Rose and Freshfields Bruckhaus Deringer have had their path to limited liability partnership (LLP) eased after a breakthrough in the French tax treatment of UK LLPs.

A ruling by the French tax authorities last month has confirmed that French partners in UK LLPs will not be subject to double taxation.

The move will allow a raft of major UK firms to convert as well as smoothing the way for Lovells' and Linklaters' planned conversion on 1 May.

Lovells' Paris partners had faced the prospect of losing their voting rights and becoming employees of the firm once it became an LLP. The ruling means they can retain their full partnership status.

Those firms that have already converted, which include Allen & Overy (A&O) and Herbert Smith, should now be able to bring their French partners under the umbrella of their LLPs.

The ruling signals a victory for the combined lobbying efforts of Linklaters, Lovells, Freshfields and Ashurst, who were assisted by Bruno Gibert, of CMS Bureau Francis Lefebvre. Although last month's decision was only announced to firms that has applied in France to become LLPs, it will apply to firms in similar situations and is due to be posted on the website of the French Government's taxation department shortly.

Philippe Derouin, a tax partner at Linklaters in Paris, told Legal Week: "I was confident that I would obtain the ruling, but I just did not imagine it would take two-and-a-half years – I think it is a record. It is good news for firms generally and confirms the law in France is not as stupid as people thought."

A&O partnership expert Richard Turnor said: "It is obviously hugely helpful because the position in France has been holding a lot of people up for a long time. A lot of firms will now be able to go ahead and those firms that have already done so will be able to unscramble the arrangements they made to get around the French rules.

"It is much more sensible if your French partners can be members of the UK LLP, with a share of the profits."