42 CFR §403.251

1. (a)Initial calculation date means the first date of the period that the insuring organization uses to calculate the policy's expected loss ratio.
   1. (1)The initial calculation date may be before, the same as, or after the date the insuring organization sends the policy to CMS for review, except—
   2. (2)The initial calculation date must not be earlier than January 1 of the calendar year in which the policy is sent to CMS.
2. (b)Loss ratio calculation period means the period beginning with the initial calculation date and ending with the last day of the period for which the insuring organization calculates the policy's scale of premiums.
3. (c)To calculate “present values”, the insuring organization may ignore discounting (an actuarial procedure that provides for the impact of a variety of factors, such as lapse of policies) for loss ratio calculation periods not exceeding 12 months.