Every other month, we have staff who disappear the day after getting their salary. They're supposed to give one month notice or pay one month's salary. People either give the required notice, or if they cannot wait that long, we calculated how many days "short" their notice is, and they "pay back" the pro-rated equivalent for that number of days.

This "pay back", is always a deduction of any salary we owe them. It has never ever happened that they actually give any money back to the company. Many of the staff don't bother. They keep quiet till the day they get their salary, and they don't turn up the next day.

It depends on what kind of job you're doing, and your position. The more senior, the less likely they are to do this. Leaving in this way always results in some loss. The salary is paid a few days after the end of the month, you lose any unpaid commission, and annual leave entitlement, etc.