During the Obama Administration, the two federal agencies primarily responsible for administering the private health insurance provisions in the Affordable Care Act (ACA)—the Centers for Medicare & Medicaid Services (CMS) within the Department of Health and Human Services (HHS), and the Internal Revenue Service (IRS) within the Treasury Department—took a series of actions to delay, extend, or otherwise modify the law's implementation. This report discusses selected administrative actions taken by CMS and the IRS through February 2015 to address ACA implementation. The report is no longer being updated and is available primarily for reference purposes. Table 1 summarizes the more significant administrative actions taken, all of which focused on implementation of the ACA's complex set of interconnected provisions to expand private insurance coverage for the medically uninsured and underinsured. These actions were not the result of a single policy decision. Instead, they represented many separate decisions taken by the Obama Administration to address a variety of factors affecting the implementation of specific provisions of the law. The Administration announced a series of delays and other changes before and during the first (i.e., 2014) open enrollment period and the problematic launch of the federal—and some state-run—exchanges. The second (i.e., 2015) open enrollment period that closed on February 15, 2015, experienced far fewer administrative and technical problems. Other administrative actions largely focused on the ACA's tax provisions. The 2014 tax filing season (deadline April 15, 2015) was the first one in which individuals were required to indicate on their tax return whether they had health insurance coverage that meets the ACA's standards. Those without coverage risked being penalized unless they could claim an exemption. In addition, everyone who enrolled in coverage for 2014 through an exchange and received advance payments of the premium tax credit had to file a federal tax return in which they reconciled those payments with the actual tax credit to which they were entitled. In compiling the table, CRS made decisions about which administrative actions to include, and which ones to leave out. Generally, CRS included the more significant actions that had been the subject of debate among health policy analysts and, in many instances, the target of criticism by opponents of the ACA. It is important to keep in mind that the table is not—nor was it intended to be—a comprehensive list of ACA-related administrative actions. The table entries, which are grouped under general topic headings, are not organized in any particular priority order. Each entry includes a brief summary of the action and some accompanying explanatory material and comments to help provide additional context. Where available, links are provided to relevant regulatory and guidance documents online. Readers are encouraged to review these documents for more details about each action, including the motivation and legal authority for taking it. A companion CRS report summarizes all the legislative actions taken by the 112 th , 113 th , and 114 th Congresses to repeal, defund, delay, or otherwise amend the ACA. Perhaps the most controversial administrative action taken by the Administration was its decision to delay enforcement of the ACA's "employer mandate." On July 9, 2013, the IRS announced that it would not take any enforcement action against employers who fail to comply with the law's employer mandate until the beginning of 2015 (see Table 1 ). This ACA provision, which took effect on January 1, 2014, requires employers with 50 or more full-time equivalent employees (FTEs) to offer their full-time workers health coverage that meets certain standards of affordability and minimum value. Those employers who do not provide such coverage risk having to pay a penalty if one or more of their employees obtain subsidized coverage through an exchange. The IRS subsequently announced that employers with at least 50 but fewer than 100 FTEs will have an additional year to comply with the employer mandate (see Table 1 ). According to the Administration, these actions were taken after it was concluded that the ACA's employer mandate could not be enforced until the related requirement that employers report the coverage they offer to their employees had been fully implemented. The IRS indicated that it would work with stakeholders to simplify the reporting process consistent with effective implementation of the law. Other controversial administrative actions include those taken in response to the decision by insurers to cancel individual and small-group health plans that do not meet the ACA's new standards for health insurance coverage, which also took effect on January 1, 2014. On November 14, 2013, the Administration notified state insurance commissioners of the option to delay enforcement of certain health insurance reforms under the ACA. It encouraged state officials to permit insurers to renew noncompliant policies in the individual and small-group market for policy years starting between January 1, 2014, and October 1, 2014. The Administration subsequently extended this policy for two years. Thus, at the option of state regulators, insurers could continue to renew noncompliant policies at any time through October 1, 2016 (see Table 1 ). The Administration was criticized for creating numerous special enrollment periods that enable individuals to enroll in an exchange plan outside the annual open enrollment period. Individuals can qualify for a special enrollment period as a result of a variety of events that affect their ability to obtain or maintain health insurance coverage (e.g., moving, losing job-based coverage, gaining legal U.S. residency). Special enrollment periods were also established for individuals unable to begin or complete the process of enrolling in an exchange plan before the end of the open enrollment period because of technical problems or other circumstances. State-run exchanges were encouraged to adopt special enrollment periods similar to the ones established for federally facilitated exchanges. In addition, the Administration established numerous hardship exemptions from the ACA's "individual mandate" penalty. Under the law, most U.S. citizens and legal residents are required to maintain ACA-compliant health coverage beginning in 2014. Those without coverage for three or more consecutive months are subject to a penalty unless they meet one of the statutory exemptions, or qualify for one of the health coverage-related or hardship exemptions established by CMS. In some instances the hardship exemption is tied to qualifying for a special enrollment period. For example, individuals who qualified for a special enrollment period to finish enrolling in an exchange plan after the 2014 open enrollment period closed on March 31, 2014, were granted a hardship exemption so that they would not be penalized for being uninsured for the first four months of the year (see Table 1 ). Opponents of the ACA, who believe that the law is fundamentally flawed, argued that some of the Obama Administration's actions were effectively rewriting the ACA in an effort to make it work and add to the public's confusion about the law. The ACA's critics asserted that the actions taken by the Administration to delay enforcement of the employer mandate were illegal and raised concerns that the President was not upholding his constitutional duty to faithfully execute federal law. The Administration countered that its actions were not a refusal to implement and enforce the ACA as written. Instead, they represented temporary corrections necessary to ensure the effective implementation of a very large and complex law. Agency officials pointed to a number of factors that made it difficult to meet various ACA deadlines. Those factors included a lack of appropriations to help fund implementation activities, technological problems including the poorly managed launch of the websites for the federally facilitated exchanges and some state-run exchanges, and the need to phase in the various interconnected parts of the law so as to avoid unnecessary disruption of employment and insurance markets. Regarding the delay of the employer mandate, the Administration said that its actions were no different from those taken by previous administrations faced with the challenges of implementing a complicated law. The Administration noted that its decision to grant employers "transition relief," taken pursuant to administrative authority under the Internal Revenue Code to "prescribe all needful rules and regulations" to administer tax laws, was part of an established practice to provide relief to taxpayers who might otherwise struggle to comply with new tax law. Notwithstanding the Administration's arguments, critics question whether some of the recent delays of ACA provisions exceed the executive's traditional discretion in enforcing law to the point that they represent a blatant disregard of the law. For example, they argue that the decision to encourage states to allow insurers to renew noncompliant policies for people who want to keep their current plans directly contravenes provisions of the ACA that had become politically inconvenient. On July 30, 2014, the House voted 225-201 to approve a resolution ( H.Res. 676 ) authorizing Speaker John Boehner, on behalf of the House, to sue the President or other executive branch officials for failing to "to act in a manner consistent with [their] duties under the Constitution and laws of the United States with respect to implementation of the [ACA]." The Speaker indicated that any such lawsuit would specifically challenge the Administration's delay of the ACA employer mandate. "In 2013, the President changed the health care law without a vote of Congress, effectively creating his own law by literally waiving the employer mandate and the penalties for failing to comply with it," said Mr. Boehner. A lawsuit was filed on November 21, 2014, consisting of two counts. First, it claimed that the Administration had violated the Constitution by delaying the ACA employer mandate. Second, the lawsuit challenged the ACA's cost-sharing subsidies. These are paid to insurance companies to reduce the out-of-pocket health care costs of certain individuals and their families receiving premium tax credits. Unlike the premium tax credits, for which the ACA provided a permanent appropriation, the lawsuit argues that the law did not appropriate any funding for the cost-sharing subsidies.