  Many active stars are covered in spots, much more so than the Sun, as
indicated by spectroscopic and photometric observations. It has been predicted
that star spots induce non-zero intrinsic linear polarization by breaking the
visible stellar disk symmetry. Although small, this effect might be useful for
star spot studies, and it is particularly significant for a future polarimetric
atmosphere characterization of exoplanets orbiting active host stars. Using
models for a center-to-limb variation of the intensity and polarization in
presence of continuum scattering and adopting a simplified two-temperature
photosphere model, we aim to estimate the intrinsic linear polarization for
late-type stars of different gravity, effective temperature, and spottedness.
We developed a code that simulates various spot configurations or uses
arbitrary surface maps, performs numerical disk integration, and builds Stokes
parameter phase curves for a star over a rotation period for a selected
wavelength. It allows estimating minimum and maximum polarization values for a
given set of stellar parameters and spot coverages. Based on assumptions about
photosphere-to-spot temperature contrasts and spot size distributions, we
calculate the linear polarization for late-type stars with $T_{\rm eff}$ = 3500
K - 6000 K, log$g$ = 1.0 - 5.0, using the plane-parallel and spherical
atmosphere models. Employing random spot surface distribution, we analyze the
relation between spot coverage and polarization and determine the influence of
different input parameters on results. Furthermore, we consider spot
configurations with polar spots and active latitudes and longitudes.
