Fixing tax accountability mandates fixing income accountability. Once that is done corruption will become impossible.

Best bet currently is cashless transactions. The more we have them, the better. If some one has more than explainable income in the bank they will be forced to show that up in tax returns, if its legal they will have to pay taxes, if its illegal then they face action.

Cash transactions are at the core of why everyday corruption is even possible. Liquid cash is easy to exchange without traceability.