Switch Medigap insurance companies

[CWradio]

I recently switched from Mutual of Omaha to AARP UHC (Plan G) Medigap insurance companies.
I checked Medicare.gov and it still show the Mutual of Omaha Medigap plan.
Does anyone know how long it takes for this change to take place?
I understand it is done by a file called crossover. Thanks

 

[anethum]

When I switched my plan G from Mutual of Omaha to AARP UHC, it took effect on the 1st of the next month. If you call AARP UHC, they should be able to tell you your start date. I don't recall needing to notify Mutual of Omaha. I don't know anything about a file called crossover.