Section 406.33 - Determination of months to be counted for premium increase: Enrollment(a)Enrollment before April 1, 1981 or after September 30, 1981 and before January 1, 2023. The months to be counted for premium increase are the months from the end of the initial enrollment period through the end of the general enrollment period, the special enrollment period, or the transfer enrollment period in which the individual enrolls, excluding the following:(1) Any months before September 1973.(2) For premiums due for months after May 1986, any months beginning with January 1983 during which the individual was enrolled in an employer group health plan based on the current employment of the individual or the individual's spouse.(3) Any months during the SEP under § 406.24 of this subpart, during which premium hospital insurance coverage is in effect.(4) Any months that the individual was enrolled in an HMO or CMP under part 417, subpart K of this chapter as described in § 406.21(f) .(5) For premiums due for months after December 2006, any months during which the individual met the requirements for a SEP under § 406.25(a) of this subpart.(6) Any months during the 6-month SEP described in § 406.25(b) of this subpart during which premium hospital insurance coverage is in effect.(b)Enrollment during the period April 1 through September 30, 1981. The months to be counted for premium increase are the months from the end of the initial enrollment period through the month in which the individual enrolled, excluding any months before September 1973.(c)Enrollment on or after January 1, 2023. The months to be counted for premium increase are the months from the end of the initial enrollment period through the end of the month in which the individual enrolls, excluding both of the following: (1) The months described in paragraphs (a)(1) through (6) of this section.(2) Any months of non-coverage in accordance with an individual's use of an exceptional conditions SEP under § 406.27 provided the individual enrolls within the duration of the SEP.(d)Examples.(1) John F's initial enrollment period ended July 1979 but he did not enroll until January 1980. The months to be counted are August 1979 through March 1980. Since only 8 months elapsed, there is no premium increase.(2) Mary T's initial enrollment period ended in April 1980 but she did not enroll until May 1981. The months to be counted are May 1980 through May 1981. Since 13 months has elapsed, the premium would be increased by 10 percent.(3) Effective with July 1986, Mary T, in Example 2, would no longer have to pay an increased premium because she had paid it for twice the number of full 12-month periods during which she could have been, but was not, enrolled in the program.(4) Vincent C's initial enrollment period ended August 31, 1986. He was covered under his wife's employer group health plan until she retired on May 31, 1989. He enrolled during June 1989, the first month of the special enrollment period under § 406.21(e) . No months are countable for premium increase purposes because the exclusions of paragraph (a) of this section apply to all months.(5) Terry P enrolled in the 1987 general enrollment period, with coverage effective July 1987. There were 28 months after the end of his initial enrollment period through the end of the 1987 general enrollment period. His premium is increased by 10 percent. The increase will be eliminated after he has paid the additional 10 percent for 48 months.48 FR 12536, Mar. 25, 1983. Redesignated at 51 FR 41338, Nov. 14, 1986, as amended at 53 FR 47203, Nov. 22, 1988. Further redesignated and amended at 57 FR 36014, Aug. 12, 1992; 73 FR 36468 , June 27, 2008; 87 FR 66505 , Nov. 3, 2022