The mutual benefit corporation is created under California law.
For federal income tax purposes - that is a corporation - unless you specifically apply for the tax exempt status - and received a recognition letter from the IRS.
Mutual benefit corporations are organized for the benefit of their own members. Some examples of mutual benefit corporations are - homeowners associations, private clubs, trade and professional associations., etc.
For instance - if your are a HOA - That is ONLY option to file 1120H - when the tax return timely filed.
Electing To File Form 1120-H. A homeowners association elects to take advantage of the tax benefits provided by section 528 by filing a properly completed Form 1120-H. The election is made separately for each tax year and generally must be made by the due date, including extensions, of the income tax return....If the association does not elect to use Form 1120-H, it must file the applicable income tax return, for example, Form 1120, U.S. Corporation Income Tax Return.
So far - you would be required to file form 1120 if you file late.
There is NO gross revenue threshold to use form 1120H - that is an option available when election is timely made.
Otherwise ANY HOA - large or small - may elect to use 1120H .