Ran across the following. I bolded the info regarding acro.

Wes

Aerobatic Pilots and ADS-B

By Dave Hughes, FAA writer

March 15, 2018 - As of January 1, 2020, ADS-B “out” will be required in most controlled airspace. Pilots who are practicing aerobatics, performing in an air show, or competing in an event will also be required to report their position via ADS-B out. This requirement is no different from the current requirement to use an operating transponder for these types of flight operations. The FAA maintains that the ability of controllers and other pilots to identify and track aerobatic aircraft via ADS-B will enhance safety.

ADS-B out is valuable for safety when an aerobatic aircraft is not performing dynamic maneuvers. It will transmit an aircraft’s identity and position to controllers and pilots of other aircraft equipped with ADS-B “in,” even if their aircraft is not being tracked on radar. Equipping with both ADS-B out and in will help pilots of aerobatic aircraft travel safely to and from events.

It is important to note that ADS-B equipment does not function properly during aerobatic maneuvers, but the FAA has said it will not penalize any pilot in that situation.

The FAA is developing a new policy on the aerobatic use of ADS-B, which should become available in summer 2018. The policy will be accessible in the FAA’s Flight Standards Information Management System (Order 8900.1) and advisory circular, AC 91-45D, Waivers: Aviation Events.

The FAA policy for ADS-B is being written in the same way as for transponders. The transponder rule has no waiver under 14 CFR section 91.205. With few exceptions, pilots are required to turn on the transponder. For instance, while in formation when aircraft are not separated during the maneuvering sequence, only the lead aircraft will need ADS-B turned on. These exceptions must be authorized by the controlling FAA facility in advance.