The Vanuatu Daily Post reports Jay Ngwele resigned on 10 January in order to receive his gratuity payment before 22 January.
Mr Ngwele said he intended to use the gratuity to help people in his electorate.
As a candidate in the next election, he would be prevented by law from doing this, if the gratuity was paid after the term ended.
Mr Ngwele said people on Ambae were still struggling to cope with the impact of their island's volcanic eruptions.
Its population of about 11,000 was evacuated in 2017 and again in 2018, to nearby islands.
Since then, several thousand have returned but are reported to be struggling to rebuild their lives.