The upshot of this, the report says, is inadequate taxpayer service, erosion of taxpayer rights, and reduced tax compliance. The Advocate expressed her continuing concern that the IRS’s expanding use of automated processes to adjust tax liabilities is causing harm to taxpayers and recommended that Congress enact a comprehensive Taxpayer Bill of Rights.

“The overriding challenge facing the IRS is that its workload has grown significantly in recent years, while its funding is being cut,” Olson said in releasing the report. “This is causing the IRS to resort to shortcuts that undermine fundamental taxpayer rights and harm taxpayers – and at the same time reduces the IRS’s ability to deliver on its core mission of raising revenue.”

The sharp increase in the IRS’s workload is due to several factors, including the increasing complexity of the tax code and the code’s frequent changes, the need to provide service to an increasingly diverse taxpayer population, the IRS’s increasing responsibility for administering economic and social policies, a surge in refund fraud and tax-related identity theft, and the implementation of new third-party information reporting requirements.

There were approximately 4,430 changes to the tax code from 2001 through 2010, an average of more than one a day, including an estimated 579 changes in 2010 alone. The IRS must explain each new provision to taxpayers, write computer code so it can process returns affected by the provision, and train its auditors to identify improper claims.

In addition, the report says, an expansion of refundable credits in recent years – including the First-Time Homebuyer Credit, the Making Work Pay credit, the American Opportunity tax credit, the health care premium tax credit, the adoption tax credit, and the Additional Child Tax Credit – has helped spawn an increase in illegal activity that seeks to profit off the tax system by filing bogus refund claims and often by stealing and using another taxpayer’s identity. While refundable credits provide valuable benefits to the target populations, they can be tempting targets for fraud because taxpayers eligible for them may claim refunds that exceed the amount of taxes they have paid. In 2011, the IRS’s Electronic Fraud Detection System flagged 1,054,704 returns on suspicion of fraud, an increase of 72 percent over 2010. Meanwhile, the IRS’s centralized Identity Protection Specialized Unit received more than 226,000 identity theft-related cases, an increase of 20 percent over 2010.

“Each year,” Olson wrote, “the IRS’s task in identifying these claims has become more challenging, with the inevitable result that some fraudulent claims are never identified and many legitimate claims are mistakenly held up, imposing a significant burden on honest taxpayers.”

The report recommends that Congress develop new budget procedures designed to fund the IRS at a level that will enable it to meet taxpayer needs and maximize tax compliance, with due regard for protecting taxpayer rights and minimizing taxpayer burden.

The report also urges Congress to codify a Taxpayer Bill of Rights that would clearly list the major rights and responsibilities of taxpayers. “The US tax system is based on a social contract between the government and its taxpayers,” Olson wrote. “Taxpayers agree to report and pay the taxes they owe and the government agrees to provide the service and oversight necessary to ensure that taxpayers can and will do so.”

Federal law requires the National Taxpayer Advocate to submit an Annual Report to Congress that identifies at least 20 of the most serious problems encountered by taxpayers and makes administrative and legislative recommendations to mitigate those problems. Overall, this year’s report identifies 22 problems, provides updates on four previously identified issues, makes dozens of recommendations for administrative change, proposes 13 recommendations for legislative change, and analyzes the 10 tax issues most frequently litigated in the federal courts.