Check out the revenue sources for the 1st 10 yeas in this screen capture from the report. I have highlighted the off budget revenues ($214.3 billion) in red. These are mostly from social security payroll taxes. Keep in mind most of the newly legalized immigrants will be years from retirement and the few that are close won't have a lot of years paying in to raise their benefit level. As you might expect off budget the outlay in the 1st ten years is very small. Actually, it's only $2.6 billion (highlight in blue) of the expected $216.8 billion in expected new spending. If you don't consider off budget items such as social security, there is a $14.2 billion deficit. When you consider how optimistic and wrong most CBO projections are (take a look at their first Obamacare projection compared to the most recent), this deficit will balloon significantly in later years. The social security and medicare for these new immigrants will have to be paid eventually.