Black shoes can be worn with tan pants. The rules for casual apparel are less constricting than those normally followed in formal wear, where black shoes with lighter pants may seem too stark a contrast.
Black shoes provide a neutral base to almost any outfit and go well with black pants, colored pants, and light brown, tan or beige pants. Choosing black shoes with brown accents reduces the contrast between shoes and pants, which may be more pleasing to some individuals. Heavier, blockier shoes, such as boots, are more noticeable and may draw more attention, which means you'll want to match them closely to pants colors.