It is easy to say that a company should be separated, but difficult to make it happen. That’s especially true for the planned disbandment of Ernst & Young, whose partners will vote in the coming months to separate the company’s consulting business from its auditing division. Strategically, it has traction. Logistically and mathematically, this is a number cruncher’s nightmare.

EY broke up because regulators in the UK and other countries wanted it, but also because it made sense. Accounting firms are often unable to audit companies that are also consulting clients, so being two separate firms, perhaps with a registered consultant, would allow EY to squeeze all the juice out of it. CEO Carmine Di Sibio estimates that it could generate $10 billion in revenue, on top of the $45 billion a year the group now earns.

But in practice it is not at all easy. Unlike a listed company, where shareholders can only vote once to approve the separation, the EY must organize local voting in approximately 75 countries. In some, a simple majority will suffice, in others it requires two-thirds support. In some places one vote is cast for each member; in other countries, power is distributed according to the capital each person has. And elsewhere, partners with certain accounting qualifications enjoy separate votes.

Determining the valuation is no less problematic. If the company is split, the audit partners will exchange their share in consulting for the consultant’s share in the audit business. The audit partner will receive some cash to balance everything. But the assessment will be based on assumptions. Consulting pricing isn’t all that difficult: Rival Accenture is trading below three times its expected earnings this year, according to Refinitiv. But none of the major US consultants are publicly traded.

EY sold its original consultancy in 2000 to computer company Capgemini in exchange for shares. The partners watched in despair as the buyer’s shares plunged 95% in two years, and then EY rebuilt their consultancy after the non-competitive agreement expired. This time there is no need to worry about the buyer’s actions, but judgment is still important. The owner of the company is also the employee, so an agreement in which one party is much better than the other can lead to dissatisfaction among the workers. Auditors and consultants are trained to be critical of agreements and judgments; getting them to comply with this plan will test JE.

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