“he Internal Revenue Service is struggling to collect a new tax that’s critical to financing the president’s health care law – and auditors say the IRS’s flawed collecting process is allowing it to raise only three-quarters or so of the revenue that was originally expected.A new report from the Treasury Inspector General for Tax Administration (TIGTA) flags the enforcement of the medical device excise tax, one of a handful of new taxes imposed under the Affordable Care Act.Related: Obamacare’s Next Challenge: IRS VerificationThe Affordable Care Act’s excise tax – equal to 2.3 percent of the sales price of medical devices – took effect in January and is estimated to bring in about $20 billion through 2019, the Joint Committee on Taxation has said.Auditors say the IRS had originally estimated that the tax would bring in about $1.2 billion in the second and third quarters of 2013 – but it’s only received $913.4 million.”