Does Phyrexian mana count toward your commander's color identity?

A card's color identity in Commander is determined by every mana symbol that appears anywhere on the card — in its mana cost, rules text, or anywhere else (CR 903.4). Phyrexian mana symbols, such as {W/P} or {U/P}, are hybrid-style symbols that include a color, so they count as that color for identity purposes.

This means if your commander has {W/P} in its mana cost or rules text, white is part of its color identity, and your deck may include white cards. Conversely, you cannot include a card with {W/P} in its text in a non-white-identity deck, even if you always intend to pay 2 life instead of {W}.

The key rule is CR 903.4: 'A card's color identity is its color plus the color of any mana symbol in that card's mana cost or rules text.' Phyrexian mana symbols are explicitly color-bearing symbols under CR 107.4f, which states they are colored hybrid mana symbols.

Example: Surgical Extraction has {B/P} in its mana cost. Even though you can pay 2 life to cast it without spending mana, its color identity is Black. You cannot include Surgical Extraction in a colorless or mono-Green commander deck.

So the verdict is unambiguous: Phyrexian mana symbols fully contribute their associated color to a card's color identity for deck-building purposes in Commander.