Jan 12 (Reuters) - Citigroup's Chief Financial Officer Mark Mason said on Friday the bank expects its headcount to be down roughly 20,000 by 2026.

The third-largest U.S. bank reported a $1.8 billion loss for the fourth quarter on charges related to refilling a government deposit insurance fund and other one-off costs. (Reporting by Manya Saini in Bengaluru; Editing by Krishna Chandra Eluri)