A number of tax laws that had been scheduled to expire for 2014 were passed into law on December 16th to be effective for all of 2014. The bill containing these laws is known as “The Tax Extender Bill.”
These tax laws are scheduled to expire at the end of 2014, which means that if they are to be part of tax laws in 2015, they will need to be passed again.
Congress.gov has a summary and details on The Tax Extender Bill that you can read here:
https://www.congress.gov/bill/113th-congress/house-bill/5771