It’s the tax at the heart of Obamacare, but just more than 1 percent of Americans will end up paying it, according to an analysis by the Congressional Budget Office.  

The CBO and the Joint Committee on Taxation (JCT) slashed their estimates for how many people will pay the individual mandate tax penalty in 2016 by a third — to 4 million from 6 million — citing exemptions granted by the Obama administration, including exemptions for people whose plans were cancelled because they did not meet the Affordable Care Act’s requirements.  

That’ll lead to $4 billion in revenue in 2016 and $5 billion a year after that — a drop of about $3 billion a year. It will still generate $46 billion over a decade, the CBO said Thursday. CQ Roll Call’s Rebecca Adams has reported extensively on this issue, noting that the IRS isn’t expected to do much to enforce the mandate anytime soon .  

There are also numerous exemptions that mean 87 percent of the 30 million people who will still be without insurance will be able to avoid the tax.  

That includes illegal immigrants — who aren’t eligible for Obamacare benefits — and low-income people.  

Adams detailed the list of Obamacare exemptions here .  

The mandate penalty will rise in 2016 to a minimum $695 per uninsured adult or 2.5 percent of adjusted gross income from $95 or 1 percent this year.  

It’s considered the heart of the law and key to the ban on discriminating against people with pre-existing conditions.  

That’s because without it, many people would choose to wait until they are sick to buy insurance, driving up premiums. In turn, more people would forgo insurance.  

Insurance companies have repeatedly argued for a robust mandate to buy insurance, warning of a death spiral without it.  

The CBO had projected the law would cut the deficit significantly, especially in the second decade as provisions like a tax on “Cadillac” insurance plans start to kick in.  

But as CQ Roll Call reported this week, the CBO has given up estimating the cost of the law. The latest CBO report was requested by Sen. Orrin Hatch, R-Utah, the ranking member of the Finance Committee. He issued a statement reiterating a call for repealing the individual mandate.