	Introduction

There are 14 U.S. territories, or possessions, five of which are inhabited: Puerto Rico (PR), Guam, U.S. Virgin Islands (USVI), American Samoa (AS), and the Commonwealth of the Northern Mariana Islands (CNMI). Each inhabited territory's local tax system has features that help determine the structure of its public finances. The IRC also establishes interdependencies between federal and territorial tax systems, such that changes to the IRC can have economic and revenue effects in the territories and vice versa. This report summarizes U.S. tax policy related to the territories, including what federal tax policies apply to residents in each of the territories and how federal law affects the different territorial tax systems. It is not intended to be a comprehensive guide to territorial or federal tax policy or tax law. Most importantly is the distinction between the mirror code and non-mirror code tax systems. This means these territories must use the IRC as their territorial income tax law, substituting terms where appropriate (e.g., the territory's name for "United States"). Also, while these territories use the IRC as their income tax system, the tax imposed is a local tax (see Table A-1 for a discussion of how this could also affect tax filing requirements). Since then, PR has enacted its own income tax laws. First, while the United States taxes its citizens, residents, and corporations based on their worldwide income regardless of whether the income is earned within the United States or abroad, for federal tax purposes the residents of the U.S. territories are generally treated more similar to foreign citizens (even though they are U.S. citizens or nationals) and corporations organized or created in the territories are treated like foreign companies. The possession-source income exclusion currently applies to each of the territories through several sections of the IRC:
American Samoa (IRC Section 931) U.S. Virgin Islands (IRC Section 932) Puerto Rico (IRC Section 933) Guam and CNMI (former IRC Section 935)
The possession-source income exclusion and IRC tax coordination requirements between each territory and the United States will determine the filing situation of bona fide residents with income earned outside of their jurisdiction, and individuals who are not bona fide residents and earned territorial-source income. Policy Issues for Congress

This section of the report summarizes three tax policy issues relevant to the territories that could be of current interest to Congress: (1) tax-based assistance to households in the territories, (2) tax policy and economic development of the territories, and (3) tax arbitrage and U.S. tax avoidance activities related to the territories. While there are many ways to potentially structure this assistance, common proposals include (1) expanding the availability of the federal earned income tax credit (EITC) to households in the territories, (2) expanding the availability of the federal additional child tax credit (ACTC) to households in the territories, and (3) creating a payroll tax cut for territorial tax filers. Mirror code residents (Guam, CNMI, and USVI) and certain PR residents can claim the ACTC. Although a comprehensive historical analysis of U.S. tax policy toward the territory is beyond the scope of this report, notable examples include the now-repealed IRC Section 936 possessions tax credit (first enacted in 1976, but fully phased-out in 2005); deferral of tax on the earnings of territorial subsidiaries of U.S. corporations; and the federal, state, and local exclusion of interest on qualified public bonds issued by the territories. Both forms of tax incentives could be made available to encourage economic activity in any industry, or they could be structured to provide a relative boost to particular industries. Other studies, such as those by the Government Accountability Office (GAO) in 1993, provided additional evidence that the average tax benefit for 936 corporations often equaled if not surpassed average compensation per employee. Tax Arbitrage and U.S. Tax Avoidance

Tax arbitrage activity in the territories is symptomatic of the broader erosion of the U.S. tax base due to international income and profit shifting. For example, the revenue raised by shutting off these tax strategies could be used for paying down government debt or on spending programs (such as infrastructure, workforce education, or general social services) that could potentially have a larger effect on growth or income security in the territories. Non-mirror-code territories could also use this revenue to lower statutory income tax rates for all territorial taxpayers (and not just those who are granted special exemptions). Second, tax avoidance opportunities reduce economic efficiency by distorting relative rates of return to capital across locations.
There are 14 U.S. territories, or possessions, five of which are inhabited: Puerto Rico (PR), Guam, U.S. Virgin Islands (USVI), American Samoa (AS), and the Commonwealth of the Northern Mariana Islands (CNMI). Each of these inhabited territories has a local tax system with features that help determine each territory's local public finances.
The U.S. Internal Revenue Code (IRC) has two important roles in establishing the tax policy relationship between the United States and the territories. First, native residents of U.S. territories are U.S. citizens or nationals but are taxed more similar to foreign citizens because income earned from territorial sources is treated like foreign-source income. The IRC also treats U.S. subsidiaries formed in the territories as foreign corporations, which can generally defer U.S. tax on income earned from business or trade in the territories.
Second, the IRC serves as the local tax laws in the territories that are required to use a mirror-code system (USVI, Guam, and the CNMI), in which the territory substitutes its name for the "United States" to give the IRC the proper effect as the territory's local income tax system. AS is not bound by the mirror system but has chosen to adopt much of the IRC for its income tax. PR has its own income tax system, which is not based on the IRC.
These dynamics between federal and territorial tax policy raise several potential issues for Congress. First, economic development of the territories has been of perennial congressional interest. Tax incentives enacted by the territories and the United States have been shown to direct offshore investment to the territories. With this said, though, economic studies of one broader U.S. tax incentive, the now-repealed Section 936 credit, indicate that any employment effects are usually secondary to the magnitude of effects on shareholder earnings, and average tax benefit for corporations often equaled if not surpassed average compensation per employee. Tax policies that effectively subsidize a more narrow set of industries in certain territories, such as rum production in PR and the USVI and manufacturing in AS, still exist today.
Second, federal tax benefits could be used to assist low-income households living in the territories. For example, the Earned Income Tax Credit (EITC) and the additional child tax credit (ACTC) could be expanded to low-income territorial households. The EITC is typically not available to territorial residents and the ACTC is limited to residents of the mirror code territories and certain residents of PR. Although these options could target lower-income households, they could also impose administrative costs for territorial households that are not required to file U.S. tax returns (e.g., because they only have territorial-source income). A payroll tax cut could be administratively simpler (since all territorial residents withhold taxes for some federal payroll taxes), but it would also be less narrowly targeted to lower-income households.
Third, interactions and differences in tax rates between the U.S. and territorial tax policies also create opportunities for tax arbitrage and avoidance by corporations and certain individuals. For the United States, this tax revenue loss is part of a broader issue with international income and profit shifting. For the territories, the revenue lost from special tax incentives could be used to reform the local tax system, increase spending on social programs, or pay down their debt. Such tax avoidance opportunities can distort the allocation of capital away from locations and industries where investment earns the highest economic rate of return. Additionally, the ability for certain taxpayers to utilize sophisticated tax avoidance strategies could raise issues of fairness.
This report summarizes U.S. tax policy related to the territories, including a general discussion of how federal taxes apply to territorial residents and how federal law affects the different territorial tax systems in similar or different ways. This report is not intended to be a comprehensive guide to federal or territorial tax policy or tax law.