the turn of the year
At or near the end of one year and the beginning of another. The turn of the year is always my busiest period as that's when our annual audit takes place. It's a little strange because their new fiscal year starts in March, unlike most companies who start theirs at the turn of the year.
the ˌturn of the ˈcentury/ˈyear
the time when a new century/year starts: He was born around the turn of the century.