The organisation could be formed through parliamentary legislation, said Somchai Jitsuchon, research director at the Thailand Research and Development Institute.
Mr Somchai said the organisation should be created as soon as there is a functioning government, as one of the problems stemming from political tensions is a lack of transparency in fiscal budgetary spending intertwined with a tendency towards increasing off-budget expenditure.
The trend of populist policies in recent years has led society to keep an eye on the government's fiscal discipline, he said.
The last straw was the 2-trillion-baht borrowing bill of the Yingluck Shinawatra government that was to invest in infrastructure development projects over seven years, Mr Somchai said.
This would have allowed the government to proceed with borrowing and project investment without disruption by fiscal budget protocol.
The opposition Democrat Party strongly disagreed with the bill, saying it would allow the government to borrow huge funds without proper inspection.
It filed a case with the Constitutional Court, which ruled that the bill was unconstitutional, forcing the caretaker government to seek other ways to fund the projects.
Despite the scrapping of the borrowing plan, a new body to inspect government project investment is crucially needed, Mr Somchai said.
The body should be independent of the government’s executive branch, not connected to political parties, transparent and have expertise in fiscal budget analysis.
Theoretically, there are a few ways to establish the PBO. It could be an agency governed by the parliamentary system, an independent agency under the parliamentary system or an independent agency outside the parliamentary system while operating under the annual fiscal budget.
However, Mr Somchai said the second or third method would be preferable since the first one would provide a greater chance of political interference with the organisation.
The PBO management committee should consist of representatives from the public sector, while a director with credible skills should be selected under conditions preventing political affiliation, and the organisation should be formally scrutinised up to three times annually, said Mr Somchai.
"We hope the PBO issue will be included in the reform movement and that the new parliament will consider passing legislation to establish the PBO among other reform practices," said Mr Somchai.
He said no systematic fiscal risk assessment is in place, while accountability between the parliament and the executive branch has not been fully exercised.
Prof Sasatra Sudsawasd from the National Institute of Development Administration's School of Development Economics agreed that a Thai PBO was needed to support society in the battle against graft.
He voiced concern that one obstacle hindering the development of a PBO is that the government’s executive branch may interfere with the appointment of the organisation's director.
Prof Sasatra pointed to a current Canadian scandal in which the parliamentary budget officer is being denied access to the government's spending plans and must file requests to see information.