The International Linear Collider (ILC) is a proposed electron positron collider providing 250 GeV collisions at with a luminosity of $\sim 10^{34} \mathrm{cm^{-2} s^{-1}}$, producing $0.5 \times 10^6$ Higgs bosons.
In this contribution we describe how the ILC can measure the Higgs boson coupling to leptons,
and its CP properties via its decay to $\tau$ leptons. That the product of the Higgs production cross-section and its branching ratio ($\sigma \times BR$) can be measured to a precision of around $1.2\%$ for $h\to\tau^+\tau^-$, $20\%$ for $h\to\mu^+\mu^-$, and that the mixing angle between odd and even components of the Higgs boson can be determined to 75 mrad.