Travel Tips Customs + Immigration Two Strange Symbols That Might Appear on Your Customs Receipt — and What They Mean If you see an X or O, don't panic. By Melanie Lieberman Melanie Lieberman Instagram Twitter Melanie Lieberman is the senior travel editor at The Points Guy and was an editor at Travel + Leisure. Travel + Leisure Editorial Guidelines Published on February 10, 2018 Share Tweet Pin Email Photo: Scott Olson/Getty Images Travelers entering the United States from abroad may notice big black X or O printed on their receipt from the automated passport control kiosk (or APC). No, it is not someone's first Tic-Tac-Toe move. Related: A New App Lets You Skip Immigration Lines (No Global Entry Required) According to U.S. Customs and Border Protection, there are a number of reasons travelers may receive either of these markings on their receipt. The letters might be flagging for fingerprint recognition issues, duties that need to be paid, additional document checks, random inspections, or questions about their customs declarations forms. (Ask yourself: Did you check "yes" to hanging out with livestock during your vacation?) “International travelers using the Automated Passport Control kiosks should not be alarmed if a symbol appears on their receipt,” Stephanie Malin, a public affairs officer for U.S. Customs and Border Protection, told Travel + Leisure. Everything You Need to Know About Global Entry and TSA Pre-check Not unlike seeing an SSSS printed on your boarding pass, these codes on your APC receipt can often (though not always) indicate you're going to experience a lengthier or more involved process for entering the country, regardless of whether you’re a Global Entry-approved U.S. citizen, green card holder, or foreign tourist. “There are [also] referral codes that appear on each receipt,” Malin noted, adding that those are for “internal agency use only, and allow CBP officers to easily identify where the traveler should be routed based on the referral.” Was this page helpful? Thanks for your feedback! Tell us why! Other Submit