There is no single correct option.
http://www.gerichte-zh.ch/themen/arb...echnungen.html
Some helps:
An employee which leaves the company during the year has a pro rata entitlement to the 13th salary.
I would also support this view:
| Quote: | |  | |
| For example, if you have 8 hrs per day setup, the annual number of hours is 52 weeks x 5 days x 8 hours = 2080 hours.
If you have 10K a month paid 13x => 130K annual salary, it would give an hourly salary of 62.50 (130'000 / 2080) | |
| | |
In a leap year there is one additional day
Which decreases the hourly rate a tiny little bit.
This should also work for bookkeeping. Just treat public holidays and vacation as paid days off.