An event occurring twice each month is called semi-monthly and it is commonly related to salaries. If the pay structure is semi-monthly, employees get paid 24 times per year, most often on the 1st and 15th or the 15th and last day of each month. It differs from a biweekly system which leads to only 26 pay periods in a year. Even if both pay methods divide the whole year’s pay fairly, semi-monthly methods can be a problem for hourly staff whose payment periods are not always the same length. It is a scheduled system that is often set up for those who get salaried pay.