The Independent Commission Against Corruption (ICAC) will launch public hearings for Operation Spicer in Sydney on Monday, with Mr Tinkler due to enter the witness box on Friday.
There is no suggestion Mr Tinkler has acted corruptly.
Operation Spicer will investigate allegations that former NSW energy minister Christopher Hartcher, and others, corruptly solicited, received, and concealed payments in return for MPs favouring the interests of those responsible for the payments.
Mr Hartcher is now suspended from the NSW Liberal Party.
The allegations, which centre on a period between April 2009 and April 2012, also involve fellow suspended NSW Liberal MPs Darren Webber and Christopher Spence.
ICAC will also investigate allegations that NSW MPs, including Messrs Hartcher, Webber and Spence, solicited, received and failed to disclose political donations from companies, including prohibited donors, contrary to the Election Funding, Expenditure and Disclosures Act 1981.
Further allegations include whether the business Eightbyfive entered into agreements with a series of companies including Australian Water Holdings Pty Ltd (AWH), purportedly for media, public relations and other services, in return for Mr Hartcher favouring the interests of Eightbyfive.
Australian Water Holdings was at the centre of the most recent ICAC inquiry, which ended last week.
The then NSW premier, Barry O’Farrell, resigned after appearing as a witness at that inquiry after it emerged that he was sent a bottle of expensive wine by AWH chief executive Nicholas Di Girolamo.
AWH and some of its senior managers are alleged to have engaged in improper conduct, including passing on dubious expense claims to taxpayer-funded Sydney Water.
ICAC is due to report findings from its investigation into those allegations later this year.
ICAC Commissioner Megan Latham will oversee the Operation Spicer public hearings, which are expected to last about three weeks.