A yearly return you file yourself with the 税務署, from February 16 to March 15. It is required for freelancers, people with two jobs and people who left a company before the adjustment.
Between February and March every year.
Employees with one job usually do not need it. File it if you are a freelancer or have a refund to claim.
General explanation, for guidance. Rules and amounts change: confirm with the responsible office.