It depends
Tamari is traditionally made with little or no wheat, but some is brewed with wheat and still sold as tamari, so check the ingredients or look for a gluten-free claim — the word by itself does not settle it.
A Japanese soy sauce made with little or no wheat — historically the liquid that pools off miso as it matures, rather than a thing brewed on purpose. Standard Japanese soy sauce, shoyu, is conventionally close to half wheat by weight; tamari is the style that leaves most of that out, which is why it tastes rounder and less sharp and why it became the substitute of choice.
Because it is the word people are told to look for, and a word is not a specification. Tamari describes how something was brewed, not what is in it, and nothing stops a producer from using some wheat and still calling it tamari — several do. Somebody who has learned "tamari is the safe one" can pick up a bottle that contains wheat, and the fact that most bottles do not is exactly what makes the exception dangerous.
Buy a tamari that says gluten-free on the bottle and the question never comes up again at home. Do not carry the word itself into a restaurant as if it were a certification — the useful question there is still whether the kitchen has a gluten-free soy sauce, not whether they have tamari.
CiCi treats bare tamari as unresolved rather than safe, and clears it on a gluten-free claim like any other conditional. This entry was classed safe until October 2026, when it was found to contradict what the soy sauce page already told readers CiCi would do.
Every one of these is the same ingredient. The number of names is a large part of why gluten slips past people who read every label.
Point CiCi at the barcode on the product you're holding and get this same reasoning in about two seconds, plus the carbs and the full nutrition panel. 360,000+ packaged foods are already read and waiting.
The aisle guides below cover Tamari in context — which is usually the more useful question, because an ingredient rarely appears alone.
This answer comes from CiCi's ingredient lexicon — the same rules the scanner uses, not a separate article. Where reputable sources disagree, CiCi takes the conservative position and says so.