In April 2020 United announced that tickets issued from 5/1/19-3/31/20 would be valid for 24 months instead of the usual 12 months.
United is now extending ticket validity for tickets issued from 5/1/19-3/31/21 to be valid through 3/31/22. Tickets issued on or after 4/1/21 will once again have a 12 month validity.
If you have a cancelled ticket, it retains its value as future flight credit. That credit can now be used for flights through 3/31/22.
Alternatively, you can request that the flight credit be converted into an electronic travel certificate valid for 24 months, though United has gotten stingier about granting that conversion.
A comparison between those options can be found here, but in short, future flight credit can only be used for the original traveler and any residual value is lost when rebooking. An electronic travel certificate is valid for anyone and it retains all residual value when rebooking. Plus you can merge multiple electronic travel certificates together.
HUCA may be needed to refund a ticket or convert a cancelled ticket into an electronic travel certificate. I’d suggest starting with a DM to @United on Twitter and asking for an exception if you are denied, though you can try all of the avenues of contacting United and try asking for a manager to get it done.
Of course if United cancels your flight, you can request a cash refund. That’s why you should never cancel a flight until it’s close to the time of departure to see if the flight will be cancelled, as if you cancel first, you won’t be able to get a cash refund.
Either way, kudos to United for extending ticket validity once again!