quantum mechanics - Schrodinger equation for a Hamiltonian with explicit time-dependence?

Can I write a Schrodinger equation for time-dependent Hamiltonian like this:

$$i\hbar\frac{d}{dt}\psi(t) = H(t)\psi(t)$$

and then perform Euler integration like this:

$$\psi(t+\Delta t) = (1-\frac{i}{\hbar} H(t)\Delta t)\psi(t)$$

We can do this when $H$ is time-independent for very small $\Delta t$. But when $H$ is time-dependent is it valid to do this?