United MileagePlus (Consolidated) - US ticket, UA flight - whose rules?

I was ready to buy a SFO-BWI ticket with UA for $309.80 before I saw that I can get the same UA flight with a US ticket for $288.80. The funny thing is that both carriers show the same $278 "base" fare, but US adds only another $10.80 in taxes and fees, while UA adds $31.80. So 2 questions: i) how, if at all, does it matter to me as a UA 1K whether I buy the ticket from UA or US?; ii) why the difference in taxes and fees?

If I use my UA Visa to purchase the ticket, I'll earn a trivial dollop of extra RDM (hurray!), but UA says I'll be treated the same (no baggage fees, E+, upgrade possibilities) no matter which carrier I ticket with.

I was ready to buy a SFO-BWI ticket with UA for $309.80 before I saw that I can get the same UA flight with a US ticket for $288.80. The funny thing is that both carriers show the same $278 "base" fare, but US adds only another $10.80 in taxes and fees, while UA adds $31.80. So 2 questions: i) how, if at all, does it matter to me as a UA 1K whether I buy the ticket from UA or US?; ii) why the difference in taxes and fees?

If I use my UA Visa to purchase the ticket, I'll earn a trivial dollop of extra RDM (hurray!), but UA says I'll be treated the same (no baggage fees, E+, upgrade possibilities) no matter which carrier I ticket with.

1. It doesn't matter at all..you'll still be able to upgrade at United.com (or CPU) as a 1K, and you'll get all your other 1K benefits like E+/bags. This is one of the good things about SHARES... when UA used Apollo you couldn't upgrade code shares except at the airport on the day of the flight...making code shares things to avoid like the plague if at all possible.

2. No idea why the taxes & fees are different. I'd book the code share in this instance.

Could it be that UA has a fuel surcharge that US does not impose?

1. It doesn't matter at all..you'll still be able to upgrade at United.com (or CPU) as a 1K, and you'll get all your other 1K benefits like E+/bags. This is one of the good things about SHARES... when UA used Apollo you couldn't upgrade code shares except at the airport on the day of the flight...making code shares things to avoid like the plague if at all possible.

2. No idea why the taxes & fees are different. I'd book the code share in this instance.

SHARES is a reservation system? Does it matter to me in anyway other than the one you mentioned ("you couldn't upgrade code shares except at the airport on the day of the flight...making code shares things to avoid like the plague if at all possible")? So, now it is 6 of one, a half dozen of the other where codeshares are concerned? Do I have to do anything to get my place in the queue for a possible upgrade, or do I automatically go on a waitlist?

Thanks.

SHARES is a reservation system? Does it matter to me in anyway other than the one you mentioned ("you couldn't upgrade code shares except at the airport on the day of the flight...making code shares things to avoid like the plague if at all possible")? So, now it is 6 of one, a half dozen of the other where codeshares are concerned? Do I have to do anything to get my place in the queue for a possible upgrade, or do I automatically go on a waitlist?

Thanks.

Yes..for the unitiated.. SHARES is the name of the current UA reservations system (and was used by Continental previously). UA used Apollo before the merger..you'll see many, many complaints about SHARES here on FT because there have been a lot of issues.. however, one of the good things about it is that indeed it makes code shares "6 of one, half a dozen of the other". You don't have to avoid code shares on UA metal..and you'll automatically go on the CPU waitlist just as you would if you booked it through United.com..as long as your UA number is included in the reservation (After booking I would pull it up at United.com and add it to your profile just to be sure it's in there).

If so, can it be done online or do I have to call?

If your MP number is in the record, should be able to do online (@ united.com -- will need UA PNR). Call if you have a problem.

No MP number, no access.

Assuming that an E+ seat is available, yes. You can do it online. Just pull up the reservation with the UA PNR #, add your UA FF number (if not already there), and request the seat.

I just booked a US trip with just 2 of the 6 segments on UA metal. I used my UA FF# for the booking on the US website and was pleasantly suprised to see everything in my UA account without having to find the UA confirmation #. Even better, the system had instantly given me E+ seats for the UA portion.

I"m not sure if this is a recent improvement, but assuming it sticks, it is certainly one that I like.

1. It doesn't matter at all..you'll still be able to upgrade at United.com (or CPU) as a 1K, and you'll get all your other 1K benefits like E+/bags. This is one of the good things about SHARES... when UA used Apollo you couldn't upgrade code shares except at the airport on the day of the flight...making code shares things to avoid like the plague if at all possible.

2. No idea why the taxes & fees are different. I'd book the code share in this instance.

Since Flyertalk has trained me to avoid code shares all cost, my instinct is to react to this news with skepticism. But I'm going to try it out on a SAN-SFO one-way and see what happens.

Since Flyertalk has trained me to avoid code shares all cost, my instinct is to react to this news with skepticism. But I'm going to try it out on a SAN-SFO one-way and see what happens.

Book with confidence my friend! Allow SHARES to liberate you from code share despair.

Since Flyertalk has trained me to avoid code shares all cost, my instinct is to react to this news with skepticism. But I'm going to try it out on a SAN-SFO one-way and see what happens.
I book US code shares for domestic flights all the time now because they are often much cheaper than the equivalent United flight numbers. I've never had a problem getting CPU'd (or getting any other elite benefits) on a code share.

Just remember if you have to change your flight, you can only change to a US flight number, codeshares or US metal. This can be a pain if the US codeshare is sold out but UA is still selling tickets under its flight number.

(Yes, this has happened to me in the past.)