More details on use of ETCs : UA Electronic Travel Certificates (ETC): General Q&A, ... now 2 year life

More details on use of FFCs : How to get residual value ("future flight credit") from non-refundable flight
Issues with UA's online rebooking: Missing flights, higher prices, changed cabin, ..

***************************************
* In mid-2021, UA started a process that seems headed to unify ETCs/FFCs and expand their usability
* This is still in process but much of this wiki is out-of-date and will need to be rewritten once the dust settles
* Conversion of FFCs to ETCs are no longer an option
* Most FFCs can only be used by original traveller (some older ones have more flexibility)
* See this UA announcement (27 Sept 2021) for some insight
* However presently there are still reports of issues, inconsistencies
**************************************
In early 2020, UA changed the 1-year life of tickets and ETCs to 2 years and also change rebooked flights had to "commenced" in the original ticket's life vs the older, but unenforced "complete travel.

1) Canceled ticket credit / future flight credit (FFC) -- this is where the flight is canceled but the ticket is left open. In effect when you use this credit, it is a ticket change.
This change must be made within 1 2 years of the original purchase date. The present COVID-19 waivers state "Rebooked travel must commence within 12 24 months from the original ticket issue date". Previously there is some uncertainty if the new flight needs to be completed in the same 1-year window. In the recent past that was not true but same agents are claiming it is now required. (this may be a factor on how the ticket is changed, a simple change of date is probably limited to the original purchase 1-year window but a more significant change should be a new ticket and a new full-year window.)
The new ticket can be any itinerary that can be booked on United.com (BE tickets have additional restrictions). The online re-booking / change tool is flaky and best to re-book with an agent.
The future flight credit will be listed online as a canceled flight. The new booking has to be in the same name as the previous booking but if the future booking is cheaper (and not originally booked after 2 March 2020) you will receive an ETC for the difference. For tickets purchased after 2 March 2020, there was a no-residual phrase in the fare rules, but an ETC option in place of the FFC was readily available until 1 August 2020. Generally, pre-1 August tickets continue to have the conversion to ETC if you called. Recent reports suggest this conversion may be again available (YMMV) for some post 1 August FFC tickets. Also one recent report the ETC residual practice may be re-instated.
Future flight credit cannot be combined. You need to convert them to ETC if you want to combine more than one FFC for a new ticket.
Note: there is no 24-hour "flexible booking" for new tickets made with flight credit -- although all purchases today have no change fees.
As of 16 April 2020, appears FFC for cancellation 3 March and later, may be convertible to ETCs, check your ticket in Cancelled Flights (if any United payment types were used to book the ticket (an ETC, TravelBank credit, etc.) or purchased with Chase points, the ETC option may not be available)

Multiple reports (in Feb 2021) of FFCs have been extended to 31 March 2022

2) Electronic Ticket Credit (ETC)-- this is where the ticket is converted is a cash value credit and you have 1 2-year from ETC issuance to book a new flight and that future new flight to be completed with-in 1-year of the new booking's date. So up to a total of two three-year window.
You will / should receive a voucher code to use in the future booking (you need to keep track of this but agents can look it up).
The ETC can be used by anyone but is limited to UA/UX operated flights ( a complicated workaround may work to book partner flights).
Fairly simple to use the ETC online and multiple ETCs can be combined if needed -- but the same ETC can not directly be used by multiple passengers on the same PNR.
Note if ETC covers the entire cost of the new flight, you can not use a credit card for the flight purchase and will not receive any of the benefits that come from using a credit card.
Appears for multi-passenger PNRs, ETCs go back to the "first traveler" and not the individual traveler (as FFC). "Note: If there are multiple travelers on a reservation, the total value will be issued in one certificate to the first traveler." Unknown what happens on split PNRs.

(Unverified thought) FFC of tickets purchased 3 March or later do not have residual value, so far as we know, that does not apply to ETCs at all, so ETCs are better than FFC if canceling new ticket purchases starting 3 March 2020 (till at least 30 April).

UA's -- What’s the difference between electronic travel certificates and future flight credit?

Note the Must rebook by 12 months for FFC is presently overridden by waivers stating
A process for converting an ETC to Refund if the original situation nows qualifies for a refund

Other useful threads
Extending a Credit/Travel/ETC Voucher by booking a refundable fare?
UA Electronic Travel Certificate & Codeshares/partner flights
Now See All Your Electronic Travel Credit(s) (ETCs) on Your United.com Account!
Future Flight Credits (FFC) Available on My Trips page?

​​​​​