A Fifteen-day Notice is the notice the landlord uses if, for no specific reason, the landlord simply wants you to move out, and:
The landlord cannot serve a Fifteen-day notice to evict you at the end of the month if you have a written lease that will expire sometime after the end of the month.
The Fifteen-day notice must be given to you at least fifteen days before the end of your rental period. For most tenants this is the end of the month, but if you have a written agreement check the contract for the exact day of the month your rental period ends.
To calculate the fifteen days, you don't count the day you receive the notice. You count the next fifteen calendar days including weekends and holidays. The day after you receive the notice is day one.
If there are fifteen full days between the day served and the end of the rental period, and you do not move out by the end of the rental period, the landlord can continue with the second step of the eviction which is to file a lawsuit in court.
NOTE: If there are fewer than fifteen days between the day served and the end of the rental period, most judges will allow you to stay until the end of the next rental period. This gives you a defense to being evicted at the end of your current rental period, but you will need to be moved out by the end of your next rental period.
NOTE: If your written contract requires a 30-day notice to evict, a 15-day notice would not be proper.