The Northern Mariana Islands' Tax System is already described in detail elsewhere on this page - as a mirror-code US territory, the CNMI's assessment mechanism live-mirrors current US federal law (see Corporate/Personal Tax Rate sections above).
The CNMI follows the US federal tax year (calendar year) given its mirror-code status, with filing deadlines tracking current US federal deadlines live.
Northern Mariana Islands is one of three "mirror Code" possessions (with Guam/USVI/CNMI all mirroring each other) - the Internal Revenue Code of 1986, as amended, serves AS Northern Mariana Islands's own local corporate tax law, substituting "Northern Mariana Islands" for "United States" wherever the Code refers to the US. This means Northern Mariana Islands's corporate rate tracks the current US federal corporate rate live: 21% (the flat federal rate since the 2017 Tax Cuts and Jobs Act), not a rate frozen at an earlier point in time. CNMI's local government has at times offered its own qualifying certificate and tax rebate programs for eligible businesses - confirm current program status directly with the CNMI Division of Revenue and Taxation.
For the same mirror-code reason, Northern Mariana Islands's personal income tax uses the current US federal individual brackets directly, topping out at 37%. A bona fide resident of Northern Mariana Islands generally files and pays tax only with Northern Mariana Islands's own local tax authority rather than the IRS, and does not owe US federal income tax on Northern Mariana Islands-source income.
The Commonwealth of the Northern Mariana Islands has no conventional VAT or retail sales tax. Instead, a Business Gross Revenue Tax (BGRT) applies to business activity, with rates tiered by annual gross revenue level rather than a single flat rate - a gross-receipts tax rather than a value-added or point-of-sale consumption tax.
Northern Mariana Islands follows the federal "bona fide resident" test used across the mirror-code and non-mirror-code US territories alike: broadly, presence for at least 183 days in the tax year, no closer connection to the US or a foreign country, and a tax home in Northern Mariana Islands for the full year, per IRC Section 937 and its implementing regulations. Bona fide residents are taxed on worldwide income by Northern Mariana Islands itself (their sole filing obligation in most cases); non-bona-fide residents are taxed only on Northern Mariana Islands-source and US-effectively-connected income.
A non-US entity has a CNMI permanent establishment on the same basis as under the mirrored US Internal Revenue Code (see 26 U.S.C. Section 931 already cited elsewhere on this page).
Because Northern Mariana Islands mirrors the full US Internal Revenue Code as its own local law, it also mirrors the US's own Subpart F and GILTI (Net CFC Tested Income, NCTI, post-OBBBA) CFC regimes in their entirety - a Northern Mariana Islands-incorporated or Northern Mariana Islands-resident-controlled foreign corporation is subject to the same CFC attribution rules the mainland US applies to its own residents.
As a mirror-code jurisdiction, Northern Mariana Islands applies the same US federal interest-limitation rules as the mainland - IRC Section 163(j)'s 30%-of-adjusted-taxable-income cap on net business interest expense - rather than a separately-enacted local thin capitalization ratio.
As already described elsewhere on this page, the CNMI mirrors the full US Internal Revenue Code including its Subpart F/GILTI-NCTI CFC framework; the US's own hybrid-mismatch-adjacent provisions apply identically given the live mirror-code mechanism.
The CNMI itself has no domestic foreign-account disclosure regime, but bona fide CNMI residents are US citizens or nationals and remain fully subject to US federal FBAR (FinCEN Form 114) for genuinely foreign (non-US, non-territory) financial accounts exceeding the standard $10,000 aggregate threshold - accounts held in the mainland US or in another US territory are not "foreign" for this purpose. Notably, CNMI residents are specifically NOT required to file Form 8938 (the FATCA statement of specified foreign financial assets), unlike residents of Puerto Rico and American Samoa, who are; this is a genuinely CNMI/Guam/USVI-specific carve-out from the general FATCA individual-reporting rule, not an oversight.
As already described elsewhere on this page, the CNMI mirrors the US's own IRC Section 245A 100% dividends-received deduction for qualifying foreign-source dividends given its live mirror-code status.
As already described elsewhere on this page, the CNMI mirrors the US's own IRC Section 901 foreign tax credit regime (Forms 1116/1118) live given its mirror-code status.
Northern Mariana Islands does not independently negotiate its own tax treaties as a US territory rather than a sovereign state; its residents' treaty position depends on the interaction between US treaty law and the territory's own mirror-code status, which is a genuinely technical area - confirm treaty applicability directly with a US international tax adviser for any Northern Mariana Islands-specific cross-border structure rather than assuming mainland US treaty benefits apply automatically.