Five federal agencies are bracing for a tough year as Republicans take full control of Congress in January, when lawmakers return to Washington.

The Internal Revenue Service, Health and Human Services and the Environmental Protection Agency may all see extra scrutiny from Congress, especially when it comes to contentious issues like Obamacare.

Related: 5 More Surprises Hiding in the CRomnibus Bill

To get an idea of just how brutal things may be, consider the CRomnibus spending bill. Republicans, with little opposition from Democrats, slipped a $350 million cut to the IRS’s budget into the spending bill. The IRS has been arguably the GOP’s biggest target ever since the agency honed in on conservative groups. The agency has been scrutinized by both parties as well for excessive spending on lavish conferences, all courtesy of the taxpayer.

The cuts this year are so significant however, that IRS Commissioner John Koskinen has warned they may cripple the agency just as it takes on more responsibility under the Affordable Care Act.

These five agencies are up for extra scrutiny:

Internal Revenue Service

The GOP spent a good chunk of 2014 grilling IRS officials about targeting conservative groups. Though the scandal has not proven to reach all the way to the White House, the GOP is not done scrutinizing the IRS.

Related: 5 Most Egregious Examples of Government Waste

Health and Human Services Department

Obamacare has certainly had its problems since it became law in 2010, but a natural target of the GOP is the agency tasked with implementing the health law. HHS officials, including Marilyn Tavenner, administrator of the Centers for Medicare and Medicaid Services, have been regularly called to testify before the House Oversight and Government Reform committee over the problem-plagued website and the incomplete enrollment numbers. Tavenner and others may well be before the committee again in the New Year.

Department of Homeland Security

The DHS is charged with implementing Obama’s executive action on immigration – an independent move highly criticized by Republicans. To counter the action, Republicans created the CRomnibus, which funded the government fully until next year, except for the DHS; it will limp along until February, when Congress must approve a longer-term spending bill for that agency.

Environmental Protection Agency

Senate Majority Leader-to-be Mitch McConnell (R-KY) said during his campaign this year that his top priority in 2015 is to “do whatever I can to get the EPA reined in,” a reference to the numerous executive actions President Obama has announced to address climate change. McConnell comes from Kentucky, a coal producing state and is intent on protecting Kentucky’s economy.

Related: CRomnibus Disaster Signals Sad New Normal in D.C.

Consumer Financial Protection Bureau

The five-year-old CFPB, which regulates financial products like credit cards and payday loans, may be the most vulnerable agency under GOP control. Created under the Dodd-Frank Act and founded by liberal firebrand Elizabeth Warren, the agency has never even existed under a Republican Senate, let alone a Republican Congress. There have been many Republican attempts to limit the regulator’s power.

Top Reads from The Fiscal Times: