Let $A$ be a $\nu$-vector of self-adjoint, pairwise commuting operators and $B$ a bounded operator of class $C^{n_0}(A)$. We prove a Taylor-like expansion of the commutator $[B,f(A)]$ for a large class of functions $f:\mathbb{R}^\nu\to\mathbb{R}$, generalising the one-dimensional result where $A$ is just a self-adjoint operator. This is done using almost analytic extensions and the higher-dimensional Helffer-Sjöstrand formula.

Keywords: Commutator expansions, functional calculus, almost analytic extensions, Helffer-Sjöstrand formula.

Mathematical Subject Classification (2010): 47B47