The period she can apply for is between September 2019 and February 2020.
Explanation:
In relation to the case above, Mary's enrollment period is between September 2019 and February 2020. This is because Medigap policies are open for 6 months and this period begins to be counted from the month the client completes. 65 years old. Mary turns 65 on September 23, 2019. This means that she can apply any day in September and this period will extend to her for 6 months, ending only in February 2020.