Clive Palmer took 10 months to publicly declare he had quit the directorship of three companies linked to Queensland Nickel.
As a federal MP Mr Palmer is required to update his parliamentary pecuniary interest register within 28 days of a change, which is then published on the parliamentary website.
However, a check of the register found the Palmer United Party leader quit as a director of Queensland Nickel, QNI Resources and QNI Metals on February 16 last year but did not note that until December 10.
The register also showed Mr Palmer had remained a director of the three companies until April 5, 2014.
That is despite his telling reporters on several occasions he had not been a director of any of the companies he owned since September 2013 when he entered parliament as the MP for the Queensland seat of Fairfax.
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Mr Palmer is noted as having rejoined the board of the three companies on January 22, 2015, before quitting the directorships again on February 16.
Under parliamentary rules, any MP who "knowingly fails to notify any alteration of those interests to the registrar of members interests within 28 days of the change occurring ... shall be guilty of a serious contempt of the House of Representatives and shall be dealt with by the House accordingly".
Contempt of parliament is rarely pursued by the privileges committee, but can attract a range of penalties from a reprimand to a fine or jail.
Queensland Nickel went into voluntary administration on Monday, following the layoff of 237 workers at its Yabulu refinery on January 15.
A creditors' meeting is due to be held in Townsville on January 29 and it is understood several Australian and overseas firms are weighing up a possible purchase.
The federal government has offered a $500,000 package to help former employees find work.
Labor leader Bill Shorten says workers' entitlements should be put before any banks or vested interests.
"This exemplifies the lack of protection workers have when companies go bankrupt," Mr Shorten told reporters in Alice Springs on Friday.
He said he hoped the company could trade out of its difficulties and save the remaining 550 jobs, but in the meantime the federal government should consider better laws to protect worker entitlements and unsecured creditors.
Cabinet minister Greg Hunt said the focus should be on workers "because it's their jobs and their livelihoods and Townsville that are at risk".
Mr Palmer said in a statement he would not be commenting until after the January 29 meeting, but he urged an end to "political grandstanding".
