It's been three years since I last flew so please bear with me. Does the check-in baggage fee apply to the traveler only twice for a round trip? Do you have to pay the fee for each airplane you travel on? Also, we don't have to worry about our bags during layovers, do we? Once we check them at the first airport they should be tagged for our final destination and then we claim them there, correct?

Only once per direction, if the flights are connection (not layover of 24+ hours). So, yes, twice for a roundtrip.

As rkkwan stated IF you have a single ticket from your depature airport to your final arrival airport.

It depends. Are you flying on a single ticket with the same airlines? Or did you buy 2 separate tickets, with the 2 different airlines.

IF 1 ticket, same airlines, yes the luggage should be checked thru to your final destination.

suze, it is easily possible to have one ticket with flights on two or more airlines. And the luggage would be checked through. This is especially evident within one of the alliances, but true even with airlines not in the same alliance (for example you could have one ticket with Delta ATL-ORD and then United ORD-SFO and the bags will be checked through).

Yes i understand "could" if it is one ticket, different airlines, with mutual baggage arrangements.

But it's a for-sure thing if it is one ticket same airlines was the point I was trying to make.

From the OP I thought maybe it is even two separate tickets, so yet another scenario.

OP has not provided much detail.....

So who knows?

Also, OP may be traveling internationally so no baggage fee (unless it is between US and Canada).

Well, US carriers have started charging for international travel if you have more then one bag.

<<Are you flying on a single ticket with the same airlines? Or did you buy 2 separate tickets, with the 2 different airlines.>>

I've flown several times using two separate tickets and the luggage has been checked through to my final destination.

One exception was from Malaga to Florida and they would check it only to Atlanta. But no big deal, I had to pick it up to go through customs anyway, so just checked it back in on the second ticket.

When I checked the bag for my Florida flight, the reservationist said they could have checked it through in Malaga, but "they don't have to."