Federal employees who have trouble affording child care could get help from their agencies under rules proposed by the Office of Personnel Management to carry out an authority enacted by Congress last year. OPM says affordable childcare is increasingly difficult for a growing number of federal families to find, even when their own agencies sponsor centers. Meanwhile, some of those centers have rising vacancy rates because of cost issues. The new provision allows agencies to choose from a number of models for determining employee eligibility and the amount of the subsidy, with variations by location within an agency allowed.