A grating trim retarder fabricated from a form-birefringent multi-layer dielectric stack including at least one anti-reflection coating and supported on a transparent substrate is provided. The form-birefringent dielectric stack includes an axially-inhomogeneous element in the form of a −C-plate grating and a transversely-inhomogeneous element in the form of an A-plate grating. Each of the −C-plate and the A-plate gratings are fabricated with dimensions to form a zeroth order sub-wavelength grating structure. Fabricating the grating trim retarder with anti-reflection coatings and/or a segment where the −C-plate and A-plate grating overlap enables the in-plane and out-of-plane retardances to be tailored independently according to the desired application.