Thank you for this explanation!
ETA: If you have to pay, how do you pay it? Could you use a credit card? I don't carry that much USD when I travel, nor do I own checks.
You're welcome! You can pay with a credit card.
I just got back from Europe last week and went through the whole process again. This time, after I declared the amount we brought back which was over $1,600 ($800 for me + $800 for the DH), they moved me over to Customs where they asked a few questions, asked to see my receipts, but then didn't charge me anything. They said the DH and I would have owed just a small amount so they wouldn't bother with it. Yay!