Julie Bishop and Christopher Pyne will appear before a federal parliamentary inquiry into their compliance with ministerial rules.
The pair will explain their controversial post-politics jobs before a Senate committee in Canberra on Thursday.
Senior executives from Palladium and EY are also slated to appear, along with a representative from Transparency International Australia.
Ms Bishop and Mr Pyne have both denied breaching the code of conduct, which bans ministers for 18 months from lobbying, advocating or meeting with MPs on matters they dealt with during their time in office.
Even still, Ms Bishop has urged the government to overhaul the standards to make them more workable and enforceable.