Counting the Cost of Difference' replies to Alice Sullivan's piece on gender auditing in the UK Census. While Sullivan argues that the proposed changes to audit gender identity will dilute the meaning of 'sex' and thus the needs of women, I suggest that auditing on self-declared gender in Census 2021 signals a move towards the further recognition that gender is fluidly and diversely experienced and practiced in contemporary society. This should, I suggest, be welcomed rather than feared by feminist thinkers.