A team starts on 5 March and sets a milestone 30 calendar days later. The phrase describes a shift, so the start date is the reference and the next date is day one.
Use a calendar-day shift
Choose Shift, Add, Calendar days, 5 March as the start, and amount 30. Weekends remain ordinary dates, and the API moves across the real month length. There is no approximation that treats every month as 30 days; the operation is a LocalDate plus-days calculation.
The result is 4 April
From 5 March, one calendar day later is 6 March. Continuing through the remaining March dates and into April makes the thirtieth day 4 April. This matches elapsed calendar distance. The result would differ if the statement instead required a 30-date inclusive period beginning on 5 March.
Record “30 days later” with the date
A milestone list should retain both the calculated date and its rule. If someone later reads only “4 April,” they cannot tell whether weekends counted or whether the start was included. Saving the wording in the project task makes future changes auditable. DayCount itself stores no project or calculation history.