Chase in conjunction with UA, as a renewal benefit for certain UA MP-branded Chase credit cards, offer one-time United Club (UC) access passes. {Hyatt also offers similar passes for their top elites.} These passes offer one-time access to the UC (with any airline same day BP) on a space-available basis. No guest privileges. The pass is only for UA operated clubs, cannot be used at non-UA operated lounges.
Note: Club member/one-time pass access changes Nov 1, 2019 (same day BP on UA or partner) BP requirements change to just UA/*A

Use of passes at a particular UC / airport can be suspended due to capacity / crowding issues. This issue seems to be most common at DEN and EWR due to United Club closures/renovations going on right now; however, all United Clubs can and have denied entry to one-time pass holders due to capacity constraints.

Frequently Asked Questions

Is a boarding pass required to use a one-time pass at a United Club?
Yes, you must present a same-day United, Star Alliance, or contracted partner airline's boarding pass.

Can I use these one-time passes at partner/contract/*A lounges?
No. These one-time passes are only used at actual United Club lounges world-wide. Any lounge identified on this page as being operated by "United Club" are eligible for use with one-time passes.

Can I use one-time passes at the new United Club Fly in Denver?
Yes. Whether it's worth it to use it for a glorified grab-n-go food/drink stop is up to you.

Can I use a single one-time pass at multiple United Clubs on the same day?
No. You must surrender your day pass upon entering the club. If you plan to visit multiple United Clubs on the same day, you will need multiple day passes or purchase a United Club Day Pass which is sometimes offered through your reservation. There is anecdotal evidence of pass holders being able to use different UA Clubs at same airport -- inquire at the entry desk (it typically involves a stamp on your boarding pass and it will be very YMMV). However, no way to use the same pass at a different airports.

Are in/out privileges allowed when using the one-time pass?
Technically, no. However, it is not out of the realm of possibility if you ask the lounge attendant nicely. YMMV, though.

How many people can enter the United Club with one-time access pass?
One person per pass. Exception - UC policy is all children under 2 are not considered a formal guest.
Are minors allowed?
Yes, as long as they are accompanied by another person 18 or older (21 or older if the UA Club offers a self-service bar). Remember, one day pass per person (lap child excluded).

Can I be denied entry into the United Club?
Yes. If an United Club is near full capacity, it will no longer sell day passes. It will also deny entry to those with one-time passes initially and other eligible travelers ( UC member, *G, premier cabin,...) could be delayed on entering once capacity reaches local limits.

Are expired one-time passes still usable?
Expired one-time passes can be used for 50% off admission, up to 30 days after the expiration date.

Can I give my pass to a family member or friend? How?
Yes. Now you can e-mail passes (or generate a PDF) directly from the app to whomever you want. You can also take a screenshot of the pass in the United App and email/message that to your family member. Worst case scenario, you can also e-mail/text the 16-digit code to the one-time pass to your friend/family, and the United Club attendant should be able to key it in manually. The pass will remain in your United App until it is used by someone else at a club, so it remains available for your use (unlike a physical pass).

Can I upload/store the one-time pass in the United app?
As of Summer 2017, all new passes issued by the Chase United Explorer card are now loaded directly into the United app (or accessible on the website). You have the option of either e-mailing or generating a PDF of the pass to send to whomever you want. However, if you receive a pass from someone, you cannot save that to your United account.

I see these passes available for sale on dansdeals/eBay/Craigslist/etc? Are they valid? Is this safe?
It should be noted UA frowns on the third party trading, selling, or bartering of their coupons. As with any transaction of this type, it's always buyer beware; however, reports of issues are very rare.
The current going rate on eBay is $30-45 each for passes with a lengthy expiration date. Passes that expire in a few weeks can be had in the $20-30 range, sometimes even less, as the expiration date approaches.

I cancelled my Chase United Explorer card. Are my passes still valid?
Maybe? A user reported on 10/16/2019 that his passes remained on the United app after their UA Explorer credit card was cancelled weeks ago, and the passes worked without issue at the United Club at MCO. This goes against an earlier finding that... any unused one-time passes will be forfeited from your account--even if you printed out the barcode from the United app for later use. The time between card cancellation to pass invalidation is unknown; however, it is suggested that the passes aren't invalid until they disappear from your UA app. This is now an additional risk one needs to be wary about when buying one-time pass barcodes from eBay/Craigslist. Until there is additional proof, it's best to say: proceed with caution.

Entry is also available for $59 (as of 02/2016) at the UC itself or by purchasing within the United mobile app.

Club member/one-time pass access changes Nov 1, 2019 (same day BP on UA or partner)

Archive thread: Questions Regarding the United Club one-time pass {Archive}