Don't be surprised if you owe Uncle Sam more for the 2014 tax year.

Dozens of tax credits and benefits — on everything from supplies purchased by teachers to energy-efficient home improvements — expired on Dec. 31. While some or all of the tax breaks could be reinstated by Congress, don't count on it.

Related: Disappearing tax breaks

The Affordable Care Act's tax penalty for those who didn't enroll in health insurance for 2014 also takes effect. Taxpayers without proof of a qualified healthcare plan will have to pay a fine of $95 or 1% of income, whichever is higher.