The National Anti-Corruption Commission (NACC) will discuss on Tuesday impeachment recommendations for former prime minister Yingluck Shinawatra and the MPs and senators who voted to amend the 2007 charter in 2013.
Ms Yingluck will be banned from politics for five years if she is impeached for dereliction of duty in her role as chair of the rice-pledging scheme.
The MPs and senators may meet the same fate for voting to amend the 2007 charter to have a fully elected Senate.
NACC secretary general Sansern Poljiak said on Monday the NACC had decided both cases had grounds and would send them to the National Legislative Assembly (NLA) to proceed with impeachment.
Technically, both Ms Yingluck and the MPs and senators were no longer in office but the impeachment needs to go through so the five-year ban on them would take effect.
But on Monday, the NLA sent back the two impeachment recommendations for a former parliament speaker and an ex-Senate speaker, saying the charges were based on the already scrapped 2007 constitution.
If the NACC wants the NLA to consider the impeachment, it needs to rewrite the papers so that the offence is based on the laws in effect today and links to the NLA's mandate to impeach persons in office, said Peerasak Porchit, NLA's vice-president.
On Dec 26, 2013, the NACC found Somsak Kiatsuranont, parliament speaker, and Nikom Viyaratpanich, a former Senate speaker, guilty of malfeasance for their role in pushing the 2007 charter amendment to have a fully elected senate.
It cited they violated Section 270 of the 2007 constitution and sent the cases to the Senate to proceed with the impeachment.
After the coup, their cases were taken up by the NLA, which today found the wording and references need to be revised to fit the changing circumstances.
The NLA said impeachments cases were urgent matters to be decided in 30 days.
The NACC's move came after the NLA voted it had the authority to remove politicians from office.
Mr Sansern stressed the move was routine even though the 2007 charter had been scrapped because the 1999 organic anti-corruption law was still in force.
The law requires the NACC to recommend that the Senate impeach persons involved in a corruption case after it has found the case has grounds even though a ruling has not been made.