  We study two-dimensional spinful insulating phases of matter that are
protected by time-reversal and crystalline symmetries. To characterize these
phases we employ the concept of corner charge fractionalization: Corners can
carry charges that are fractions of even multiples of the electric charge. The
charges are quantized and topologically stable as long as all symmetries are
preserved. We classify the different corner charge configurations for all point
groups, and match them with the corresponding bulk topology. For this we employ
symmetry indicators and (nested) Wilson loop invariants. We provide formulas
that allow for a convenient calculation of the corner charge from Bloch
wavefunctions and illustrate our results using the example of arsenic and
antimony monolayers. Depending on the degree of structural buckling, these
materials can exhibit two distinct obstructed atomic limits. We present density
functional theory calculations for open flakes to support our findings.
