When you receive your income on a semi monthly pay period, it means you are paid twice a month, typically on the 1st and 15th or 15th and 30th. This pay schedule directly affects how you calculate your annual income. When filing taxes as the head of a household, it is critical to accurately report your annual income, which would be a multiplication of your semi-monthly income by the number of pay periods in a year. In this case, since you get paid twice a month, your total pay period would be 24. This ensures you claim the appropriate tax benefits and credits available for heads of households.