Non-equity partners will be forced to take on a proportionally higher degree of financial risk than their more senior colleagues as a result of the crackdown by the UK's HM Revenue & Customs (HMRC) on the taxation of limited liability partnerships (LLPs).

Changes to the way HMRC will determine the employee status of partners at LLPs from 6 April mean new and existing salaried or fixed-share partners will have to make capital contributions of at least 25% of their annual earnings to their firms.

Guidance issued by HMRC last Friday (21 February) will particularly affect junior partners within the UK LLPs of all firms – including US and international outfits. Advisers expect that most firms will now ensure all partners have contributed the required capital – or made a commitment to do so – by 5 July, paving the way for a raft of capital contributions in the coming months.

The new rules are being ushered in because HMRC believes some fixed-share partners are avoiding employee tax, despite having a guaranteed income and little decision-making power.

Daniel Sutherland, senior associate at Fox Williams, comments: "For senior associates looking for promotion to the partnership, my sense is the capital requirements would be outweighed by the benefits. However, it does expose junior partners to much higher risk – given their capital stake in the business – for little or no equity."

Several commentators suggest most junior partners will have little choice in the matter.

As a result, banks are experiencing up to 10 times more requests for loans than normal, according to Addleshaw Goddard professional practice partner Jonathan Cheney.

"If a junior partner wasn't going to contribute, that wouldn't be a career-enhancing move," adds Cheney. "It may result in a pay cut to compensate for the additional national insurance contributions (NICs).

"Either way there's less certainty for the fixed-share partner in their earnings, and a reduced residual profit pool for equity partners."

Hill Dickinson managing partner Peter Jackson – who is currently leading a consultation with salaried partners in his firm over proposals for them to contribute 30% of their salary in exchange for a small equity stake – expects the changes to have profound effects on law firm structure.

"Inevitably you are going to see the senior associate and of counsel roles being recognised more, and a more gradated step into partnership in the next 10 years or so," he comments. "Second, a clearer distinction between partners and staff will emerge, and firms will move to an all-equity partnership."

However, Ropes & Gray tax partner Brenda Coleman (pictured) does not expect the changes to materially affect partner promotion rounds.

"Law firms don't generally make up partners to save on NICs, but for sound business reasons," she explains. "I suspect that in many cases where firms have salaried partners they will accept that they are caught by the new rules and firms will have to pay the NICs."

Firms are also seeking advice on where they stand in relation to partners on guarantees, who could be treated as employees on a disguised salary.

According to some law firm advisers, the overhaul could also result in some US-headquartered firms exempting themselves from the rules altogether by abandoning their UK LLPs in preference for US models, which are not covered by the tax changes.

The new rules also state that partners who demonstrate 'significant influence' on the running of the firm will not be taxed as employees.

However, advisers say this is unlikely to be the focus for bigger firms. "None of the larger law firms expect to rely on the condition, except for management or policy committee members," says Coleman.