  The type-I seesaw model is probably the most straightforward and best studied
extension of the Standard Model that can account for the tiny active neutrino
masses determined from neutrino oscillation data. In this article, we calculate
the complete set of one-loop corrections to charged lepton flavour violating
processes within this model. We give the results both using exact
diagonalisation of the neutrino mass matrix, and at at leading order in the
seesaw expansion (i.e. $\mathcal{O}(v^2/M_R^2)$). Furthermore, we perform the
matching onto the $SU(2)_L$ invariant Standard Model Effective Field Theory at
the dimension-6 level. These results can be used as initial conditions for the
renormalisation group evolution from the right-handed neutrino scale down to
the scale of the physical processes, which resums large logarithms. In our
numerical analysis, we study the inverse seesaw limit, i.e. the symmetry
protected type-I seesaw, where the Wilson coefficient of the Weinberg operator
is zero such that sizeable neutrino Yukawas are permissible and relevant
effects in charged lepton flavour violating observables are possible. We
correlate the different charged lepton flavour violating processes, e.g.
$\ell\to\ell^\prime\gamma$, $\ell\to3\ell^\prime$, $\mu\to e$ conversion and
$Z\to \ell\ell^\prime$, taking into account the constraints from electroweak
precision observables and tests of lepton flavour universality.
