In a recent post, we covered guaranteed issue situations in general.
You can see that post on guaranteed issue Medicare supplements here.
Here, I've extracted some good content from one of the carrier's underwriting guides that helps to break down the guaranteed issue rules for California, the guaranteed issue rules for Missouri, and the Guaranteed issue rules for Oregon.
See the graphics below.. the rules on the underwriting dates in advance of the effective date, are specific to Stonebridge Life's Medicare supplement. The Enrollment starts on the birthday and lasts 30 days, not 30 days on each side. All that means is you have to take the app on the birthday or 30 days after to be GI. I am sure Stonebridge will accept apps on either side of the birthday, but no other carriers in CA that I know of will.
See this latest update from the California Dept. of Insurance:
State of Washington: