Tandem is chipped. Honestly I would have tattooed both pups except that stupid CKC never gave me my number in time. I waited for weeks for that number and my pups were 7 weeks old before they finally issued it, so I opted for microchips (as holding down a squirming puppy to get tattooed is not fun unless you put them under which I wasn't about to do). $50 per chip as opposed to $10 per tattoo... I could have died after what this litter already cost me. But they are chipped, I made sure the chips were recognised by CKC, so I guess that is all that matters. Visa is tattooed.