So, the desk-bound ladies who handle reimbursements have decided that my Air Canada itinerary in August included two baggage fees, even though their website says that checked baggage fees are assessed at the airport. I need to break down the fare calculation on my receipt to show how the numbers add up without a $25 and $35 sneaked in for both directions or else I'm out $70 for the pahntom second bags and the $25 I did have to pay on the way home when I checked a bag.

The calculation is

ATL AC X/YTO AC X/YMQ AC YQB Q ATLYQB7.50 199.00AC X/YTO AC A
TL Q YQBATL 7.50 199.00NUC413.00END ROE1.00 ZPATLYYZYULYQGYYZ
XFATL4.5

Obviously ATL, YTO, YMQ, and YQB were the airports I passed through and the ACs denote Air Canada. What's the 7.50?

199 + 7.50 + 199 + 7.50 = $413, which is the fare before taxes, so the 7.50 must be a PFC or something.

Then, later, I see:
FARE 413.00USD
US TAX 31.00
ZP TAX 20.00
XT TAX 76.00

What are the ZP and XT taxes?

Thanks for any help the forum can provide.

My guess is 7.50 is an airline credit card surcharge rather than a true tax.

AFAIK ZP is US federal passenger segment tax and XT is used for "other". Usually there are some codes which give a clue. Given the amount and your ticket being international my guess it is customs/immigration fees.

$7.50 is a US transportation tax.

XT (extra taxes) is used when you have too many taxes to list them. The XT taxes are usually breaked down in the stored fare and ticket image. Like: XT $5.00CN $21.50YTH, etc the multiple taxes then add up to the XT amount. I don't see the XT tax breakdown in your post.

Bag fees are ancillary fees, and would not be included in your ticket, ever. Unless you have a ticket designator (negotiated fare) next to the fare basis that indicates the bags are included in a negotiated fare. The only airline I know does this is AA though, with their "Choice" fares.

Plug a similar itinerary into ITA Matrix to get an idea what was charged.

The 7.50 Q surcharge is a navigation surcharge that is charged by AC.

Here is a similar itin from ITA Matrix - you can see what the tax breakdown would be

Make sure to provide the exact booking and fare codes shown.
Fare 1: Carrier AC S21Q4TG ATL to YQB (rules)
Passenger type ADT, one-way fare, booking code S
Covers ATL-YYZ (Economy), YYZ-YUL (Economy), YUL-YQB (Economy)
$206.50
Fare 2: Carrier AC S21Q4TG YQB to ATL (rules)
Passenger type ADT, one-way fare, booking code S
Covers YQB-YYZ (Economy), YYZ-ATL (Economy)
$206.50
US Transportation Tax (US) $30.98
Toronto Airport Improvement Fee (SQ) $7.20
Canadian Harmonized Sales Tax (ON) (RC) $1.00
US September 11th Security Fee (AY) $5.60
US Passenger Facility Charge (XF) $4.50
US Flight Segment Tax (ZP) $20.00
USDA APHIS Fee (XA) $5.00
US Immigration Fee (XY) $7.00
US Customs Fee (YC) $5.50
Quebec Airport Improvement Fee (SQ) $26.30
Canadian Goods and Services Tax (XG) $1.30
Quebec Sales Tax (XQ) $2.60
Canadian Air Travelers Security Charge (CA) $11.50

Subtotal per passenger $541.48
Number of passengers x1

TOTAL AIRFARE & TAXES $541.48
This ticket is non-refundable.
Changes to this ticket will incur a penalty fee.
Fare construction (can be useful to travel agents)

ATL AC X/YTO AC X/YMQ AC YQB Q7.50 199.00S21Q4TG AC X/YTO AC ATL Q7.50 199.00S21Q4TG USD 413.00 END ZP ATL YYZ YUL YQB YYZ XT 5.50YC 7.00XY 5.00XA 30.98US 20.00ZP 5.60AY 11.50CA 1.00RC 33.50SQ 1.30XG 2.60XQ 4.50XF ATL4.50