In an annual or perpetual calendar mechanism, a day-of-the-month wheel includes a notch. At each actuation of a lever, a first pawl finger effects an actuation of one step, on one of the teeth of the day-of-the-month wheel. Upon actuation of the lever at the end of a month of fewer than 31 days, a second pawl finger effects, in the notch, an actuation of the day-of-the-month wheel by a whole number of steps. The notch is positioned between two consecutive teeth among the teeth of the day-of-the-month wheel. The day-of-the-month wheel has a peripheral edge which forms the profiles of its teeth as well as the notch.

A timepiece calendar system (100), the system including a date mobile (1) pivoting about a first axis (A1), a first element (32) driving the date mobile, such as a finger, a second element (12) for driving the date mobile, including for example a tooth (12a) for driving the date mobile, the second drive element (12) being mounted on the date mobile (1) to be mobile between a retracted position and a driving position, and a month cam (22) pivoted about a second axis (A2), the month cam (22) being adapted to cooperate with the second element (12) for driving the date mobile so that, depending on the position of the month cam (22), it allows or prohibits retraction of the second element (12) for driving the date mobile, the first and second axes being distinct.