The "big four" accounting firms are structurally embedded in systematic corruption. They are "too big to fail", but sooner or later one of them will fail.

The way to end the corruption is clear: prohibit accounting companies from doing anything other than auditing.

If a sudden change is hard to implement, here's a way to force them to make them separate gradually.

Tax the consulting gross sales of accounting firms a stated percentage that rises annually. It could be 3% in the first year, 6% in the second year, and so on. I think that in 5 years they will have moved most of the consulting business to some new sister company.

The details could be adjusted so as to require splitting each current company's non-auditing work into N or more independent new companies.

Other adjustments could make them split the auditing work among a larger number of new auditing companies.