I put nearly every expense on my credit card with the goal of accumulating Southwest Airlines points so I may fly for free.

The card gets paid off each month, so no worries there. Otherwise the points would be costing me money.

Unfortunately flights aren’t totally free because passengers have to pay whatever taxes/fees governments throw at them via airlines.

I’m so used to my domestic flights on Southwest costing $11.20 round trip when I use my points. That charge is listed as U.S. 9/11 Security Fee. It’s really $5.60 one way.

“TSA has implemented congressionally mandated security fees to help finance the increased cost of securing the nation’s aviation transportation system. The revenue generated from these security fees is utilized to help ensure the safe and efficient flow of people and commerce,” according to TSA’s website.

I think anyone who flies would argue TSA has not added efficiency to the world of flying. TSA regulations are worth another story.

It’s been a couple years since I’ve flown to Mexico so I was a little surprised my flights were not quite as “free” as I expected. I was going to pay these fees no matter what airline I flew; it’s not a Southwest thing.

Flying within Mexico—mainland to Baja Sur on Viva Aerobus—I paid $12.55 for IVA, which is essentially a sales tax, along with 43 cents labeled “other airport charges”. The IVA is 16 percent.

Going into Puerto Vallarta on Southwest I was assessed the $5.60 TSA fee as well as $46.76 for what was called Mexico Tourism Tax.

It costs a whole lot more to leave Mexico and get back to the U.S. On the flight out of Los Cabos International Airport to Sacramento the ticket came with $3.84 for U.S. APHIS User Fee. APHIS stands for Animal and Plant Health Inspection Service.

The U.S. Immigration User Fee was $7, while the U.S. Customs User Fee was $7.39. Then came the $12.11 Mexico Immigration Fee and the $72.37 Mexico International Departure Tax. All of those taxes and fees amounted to $103.71 for that one-way flight.

Mexico’s departure tax may be used for all sorts of things—not just to offset the impact tourists have on infrastructure and the environment. Government officials may spend it on education, culture, sports, and health issues.

Mexico is not alone in charging a departure tax; many countries do. I’m all for paying a bit to ideally off-set my footprint in any country, but sometimes I wonder where my dollars or pesos as the case may be, really are going.