The Internal Revenue Service found that U.S. companies paid federal income taxes on their reported U.S. profits at far less than the 35% statutory rate, offering a potential revenue source for an incoming presidential administration that faces a yawning budget deficit.

Newly released data from the IRS show companies paid federal and foreign income taxes on their U.S. book income -- the amount reported to shareholders -- at a rate of 25.3% during 2005, the most recent year for which data were made available by the IRS.

Effective...