Biden’s reliance on I.R.S. enforcement to pay for $1.85 trillion bill hits a snag.

WASHINGTON — President Biden’s pledge to fully pay for his $1.85 trillion social policy and climate spending package depends in large part on having a beefed-up Internal Revenue Service crack down on tax evaders, which the White House says will raise hundreds of billions of dollars in revenue.
But the director of the nonpartisan Congressional Budget Office said on Monday that the I.R.S. proposal would yield far less than what the White House was counting on to help pay for its bill — about $120 billion over a decade versus the $400 billion that the administration is counting on.
A formal tally is expected to be released on Friday, but the projection by Phillip Swagel, who heads the budget office, could pose another setback for Mr. Biden’s domestic policy legislation, which is already facing steep hurdles in the House and Senate.
The White House has begun bracing lawmakers for a disappointing estimate from the budget office, which is likely to find that the cost of the overall package will not be fully paid for with new tax revenue over the coming decade. Senior administration officials are urging lawmakers to disregard the budget office assessment, saying it is being overly conservative in its calculations, failing to properly credit the return on investment of additional I.R.S. resources and overlooking the deterrent effects that a more aggressive tax collection agency would have on tax cheats.
“In this one case, I think we’ve made a very strong empirical case for C.B.O. not having an accurate score,” Ben Harris, Treasury’s assistant secretary for economic policy, said in an interview. “The question is would they rather go with C.B.O. knowing C.B.O. is wrong, or would they want to target the best information they could possibly have?”