In Commander, does changing your commander's zone reset the damage it has dealt for commander damage purposes?

Commander damage is a cumulative lifetime total tracked per commander, per opponent. Under the Commander rules (a supplemental format rule, not in the Comprehensive Rules proper), a player who has been dealt 21 or more combat damage by a single commander loses the game — and this total is never reset, even if the commander changes zones repeatedly.

The relevant principle is that commander damage tracking is a game-state record tied to the commander object's identity, not to any particular physical zone. CR rule 903.10a states that a player who has been dealt 21 or more combat damage by a single commander over the course of the game loses the game. The phrase 'over the course of the game' explicitly confirms the cumulative, non-resetting nature of this count.

Notably, while a commander moving to the command zone (or any other zone) can cause it to lose its history of counters or other object-specific data (CR 400.7), commander damage is tracked externally as a game record — similar to how poison counters are tracked on a player — so it is unaffected by the object's zone changes.

Concrete example: Your Voltron commander deals 15 combat damage to an opponent, then dies and is returned to the command zone. Next turn it is recast and deals 7 more combat damage to that same opponent. The total is now 22, and that opponent loses the game — the 15 damage from before the zone change was not erased.

It also does not matter if the commander is reanimated, bounced, exiled and returned, or tucked into the library and recast — the damage total always persists for each opponent who has been struck by it.