The former Auditor General, Tytti Yli-Viikari, has been refused leave to appeal her conviction on embezzlement and abuse of office charges.
Yli-Viikari had requested that the Supreme Court quash her convictions.
Helsinki District Court originally fined the former National Audit Office chief in January 2022 after finding her guilty.
Then in June this year the Helsinki Court of Appeal handed Yli-Viikari a three-month suspended jail sentence after prosecutors had appealed the verdict.
Parliament dismissed Yli-Viikari in the summer of 2021 after media reports about her use of Finnair Plus points.
Earlier this year the Helsinki Administrative Court rejected Yli-Viikari's appeal over her dismissal from the National Audit Office.