The basic idea is this: If the government auctions off the right to get the income tax revenue paid by taxpayer X diverted to the auction winner, then that winner becomes a career agent. Such an agent has an incentive to advise and promote X, just as career agents do today in acting, music, sports, etc. Such auctions are a direct substitute for government selling debt, which governments already do to convert future taxes into present revenue. Furthermore, competitive auctions will make sure the government gets paid its full value, and would also tend to pick auction winners who are actually better able to advise and promote clients X.

At the moment the government is your tax career agent, and they are doing a terrible job; they do absolutely nothing. So selling the role to someone else is a net gain if agents on average find it their interest to do some advising or promoting, and if their audiences aren’t on averaged fooled by that advice and promotion. At least if the value agents get by doing so is a lot bigger than the simple transaction costs of setting up the auction and diverting the payments, and such costs that can be made very low. Agents need not help most clients, but even if they only help 5% of clients that’s still an improvement over the status quo.