Living Out of Country with Only Part A Wants to Add Part B

I am working with a person who has been out of the country for the past several years and only has part A. (New Zealand where they have national medical.)

She has moved back to the US and wants to enroll in part B. Would she have to wait until the general open enrollment period to do this or would this somehow qualify for a special election period to get part B right away?

Thanks.

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