We report measurements of branching fractions of tau lepton decays to final states with a K-S(0) meson using a 669 fb(-1) data sample accumulated with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. The inclusive branching fraction is measured to be beta(tau(-) -> (KSX-)-X-0 nu(tau)) = (9.15 +/- 0.01 +/- 0.15) X 10(-3), where X- can be anything; the exclusive branching fractions are beta(tau(-) -> pi(-) K-S(0)nu(tau)) = (4.16 +/- 0.01 +/- 0.08) X 10(-3), beta(tau(-) -> K- K-S(0)nu(tau)) = (7.40 +/- 0.07 +/- 0.27) X 10(-4), beta(tau(-) -> pi(-) K-S(0)pi(0)nu(tau)) = (1.93 +/- 0.02 +/- 0.07) X 10(-3), beta(tau(-) -> K- K-S(0)pi(0)nu(tau)) = (7.48 +/- 0.10 +/- 0.37) X 10(-4), beta(tau(-) -> pi(-) (KSKS0)-K-0 nu(tau)) = (2.33 +/- 0.03 +/- 0.09) X 10(-4), beta(tau(-) -> pi(-) (KSKS0)-K-0 pi(0)nu(tau)) = (2.00 +/- 0.22 +/- 0.20) X 10(-5), where the first uncertainty is statistical and the second is systematic. For each mode, the accuracy is improved over that of pre-B-factory measurements by a factor ranging from five to ten. In tau(-) -> pi(-) (KSKS0)-K-0 pi(0)nu(tau) decays, clear signals for the intermediate states tau(-) -> pi(-) f(1)(1285)nu(tau) and tau(-) -> K*- K-S(0)pi(0)nu(tau) are observed.