U.S. budget deficits over the next decade will be $286 billion less than previously estimated, the Congressional Budget Office said on Monday, attributing much of the decline to lower estimates of subsidy costs under President Barack Obama's health insurance reform law.

The non-partisan CBO, in revisions to its annual budget estimates, said the fiscal 2014 deficit would fall to $492 billion from $514 billion estimated in February. The forecasts assume no changes to current tax and spending laws.