This section contains research papers, publications, and other documents dealing with taxpayer compliance and burden research. You can learn about the tax gap, specific compliance analysis issues, and studies of the causes of compliance behavior, and the drivers of tax compliance burden. Below are links to the topics within this section, as well as some examples of what you can find within each topic. Tax gap The tax gap is the difference between true tax liability for a given tax year and the amount that is paid on time. It is comprised of the nonfiling gap, the underreporting gap, and the underpayment gap. This section contains: IRS reports and presentations on the size of the tax gap for various tax years Related charts and tables Reports on reducing the tax gap Compliance analysis This section contains a wide variety of papers related to taxpayer compliance, including: Overviews of National Research Program (NRP) data Analyses of NRP data Estimates of noncompliance other than the tax gap Understanding taxpayer compliance behavior While the tax gap reflects the extent of taxpayer noncompliance, it is also important to understand why taxpayers are compliant or noncompliant. This section contains papers that seek to provide insights into taxpayer behavior through: Econometric analyses Lab experiments Field or natural experiments Other modeling Taxpayer burden research Taxpayer experience interview Affordable Care Act Premium Tax Credit Error Feedback Tax Year 2014 was the first time taxpayers had to report their compliance with the new Affordable Care Act legislation. This is a complex, potentially confusing law. The IRS wants to understand taxpayers’ and tax practitioners’ experiences preparing returns specifically with Premium Tax Credit (PTC) elements. Taxpayer and practitioner input will help IRS better plan communication and education materials and anticipate challenges faced complying with the new law.