469 NAC 1-008.03A2
A timely notice must be dated and mailed at least ten calendar days before the date that action would become effective, which is always the first day of the month.
This means that for a 31-day month, the Notice of Action is mailed no later than the 22nd day of the month; for a 30-day month, no later than the 21st day; for a 29-day month, no later than the 20th day; and for a 28-day month, no later than the 19th day, to be effective on the first of the following month.