If the House had not been dissolved, the NACC's decision means he would have to cease duties immediately. The real blow, however, is that he would be banned from politics for five years.
NACC spokesperson Vicha Mahakun said Mr Somsak had distributed to MPs a motion on constitutional amendment which was not the same as the original motion and no MPs and senators signed to endorse it as required by Section 291 of the charter.
Mr Somsak also set the deadline for amending the motion not in line with parliament regulations.
He set the deadline 15 days from April 4, 2013, leaving MPs not enough time to amend it.
His acts are in violation of Section 3, 125 and 291, which means Mr Somsak will be impeached.
The ruling will be sent to the Senate to proceed with the impeachment.