Michelle Thomson was reported to prosecutors regarding the alleged fraud after being elected as an MP in 2015.
Last August, Scotland’s Crown Office and Procurator Fiscal Service confirmed criminal proceedings would not go ahead due to “an absence of sufficient credible and reliable evidence”.
Ms Thomson has always denied any wrongdoing and has now confirmed she has since rejoined the SNP.
In a statement, she said: “Despite my preference to keep it a private matter - having received media approaches stating they have been informed I rejoined the SNP in October 2018 - I feel it is beneficial to issue a short statement in response.
“Since becoming involved in the 2014 Scottish independence referendum - and subsequently as an SNP MP - I have consistently stated that I wished to use my skills, knowledge and drive to help shape a better Scotland.
“After a number of requests from members in various parts of Scotland, I can confirm I rejoined the SNP on October 29 2018 and will be pleased to support them as they build the positive case for self-determination for Scotland.”
The statement stressed her primary focus will be on her new business, Momentous Change, which she runs with former SNP MP Roger Mullin, who also lost his seat at the 2017 general election.