The jargon, plain.

Also: EIN verification letter, Letter 147C

A replacement letter the IRS issues to confirm an existing EIN. Used when the original CP 575 is lost or when a third party (bank, state) needs independent confirmation.

Also: 25-percent foreign shareholder, 25% foreign shareholder threshold

The threshold that triggers Form 5472 reporting for a US corporation (or a disregarded entity treated as one): a foreign person holding, directly or by attribution, 25% or more of the entity by vote or value.

Also: EIN Confirmation Letter, CP-575

The IRS letter confirming your EIN assignment, sent once when the EIN is first issued. It contains the exact legal name as registered with the IRS — the authoritative source for Form 5472 intake.

Also: Certified Public Accountant

A state-licensed accounting professional in the US. CPAs can prepare and sign federal and state tax returns and (like EAs) represent taxpayers before the IRS.

Also: DE franchise tax

Delaware's annual tax on corporations formed in the state, due 1 March. Calculated under one of two methods — authorised-shares or assumed par value capital — with the taxpayer entitled to use whichever is lower.

Also: Delaware LLC tax, DE LLC $300

A flat $300 annual tax that every Delaware-formed LLC owes to the state, due 1 June. There is no annual report for an LLC — only the tax.

Also: DRE, US DE

A US business entity that exists for state-law purposes but is 'disregarded' for US federal income tax purposes — treated as a branch or sole proprietorship of its owner. The default for a single-member LLC that has not elected corporate taxation.

Also: Employer Identification Number, Federal Tax ID

A nine-digit number issued by the IRS that identifies a US business entity for tax purposes. Required to file Form 5472, open a US bank account, and submit most US tax forms.

Also: EA

A tax practitioner federally licensed by the US Treasury to represent taxpayers before the IRS. The highest credential issued by the IRS itself — equivalent in representation rights to a CPA or attorney for tax matters.

Also: FinCEN Form 114, Report of Foreign Bank and Financial Accounts

A US Treasury (FinCEN) report, not an IRS form, that a US person files when the aggregate value of their foreign financial accounts exceeded $10,000 at any point during the calendar year.

Also: FTA

An IRS administrative waiver that removes certain penalties for a taxpayer who has been compliant for the preceding three years. The simplest route to abating a first-year Form 5472 miss.

Also: Foreign-owned US disregarded entity

The specific label used on a pro-forma 1120 to identify that the filing is a Form 5472 attachment for a US disregarded entity wholly owned by a foreign person. Must be written on the header of the pro-forma 1120.

Also: U.S. Nonresident Alien Income Tax Return

The individual US tax return filed by non-resident aliens who have US-source income subject to US tax or who are claiming a treaty-based position.

Also: Foreign Person's U.S. Source Income Subject to Withholding

The information return a US withholding agent files when it has paid US-source income to a foreign person. The non-US counterpart to Form 1099 for US contractors.

Also: Non-employee compensation

The US information return filed by a business that paid $600 or more during the year to a US contractor for services. Due 31 January to both the IRS and the contractor.

Also: U.S. Corporation Income Tax Return

The US corporate income tax return filed by C-corporations. Also used in a nearly-blank 'pro-forma' version as the cover for Form 5472 when a foreign-owned LLC is a disregarded entity.

Also: S-corporation election

The election by which an eligible US corporation chooses S-corporation taxation — pass-through to shareholders — instead of the default C-corporation treatment.

Also: Information Return of U.S. Persons With Respect to Certain Foreign Corporations

The information return a US person files when they own a stake in a foreign corporation. The mirror image of Form 5472: 5471 is a US person reporting a foreign entity; 5472 is a US entity reporting a foreign owner.

Also: Information Return of a 25% Foreign-Owned U.S. Corporation

Annual information return that a US corporation (or a US disregarded entity treated as one) files when it has a 25%-or-more foreign owner and reportable transactions during the tax year.

Also: Application for Automatic Extension of Time to File

Application for an automatic six-month extension of time to file certain US business income tax returns, including the pro-forma 1120 that accompanies Form 5472 for a foreign-owned disregarded entity.

Also: Entity Classification Election

The election by which an eligible US entity changes its default US federal tax classification — for example, an LLC electing to be taxed as a C-corporation instead of a disregarded entity or partnership.

Also: Request for Taxpayer Identification Number and Certification

The IRS form a US person completes to give their taxpayer identification number to a US business that will pay them. If your US LLC hires a US contractor, you collect a W-9 from them before paying.

Also: Individual Taxpayer Identification Number

A nine-digit tax processing number issued by the IRS to individuals who need to file US tax returns but are not eligible for a Social Security Number — including non-US owners who have a US filing obligation.

Also: MMLLC

A US LLC with two or more members. Default tax treatment is a partnership (Form 1065), not a disregarded entity — which changes the US federal filing picture materially.

Also: Permanent Account Number

India's permanent tax identification number for individuals and entities, issued by the Indian Income Tax Department. Used by India-resident owners as the foreign tax ID on Form 5472.

Also: PE

A tax-treaty concept defining when a foreign company's activity in a country is substantial enough that the host country can tax its profits. The threshold is lower than most founders assume.

Also: Pro forma Form 1120, Pro-forma 1120 for a foreign-owned DE

A nearly-blank Form 1120 used as a cover sheet for Form 5472 when a foreign-owned single-member LLC is treated as a disregarded entity. Carries the header text 'Foreign-owned U.S. DE'.

Also: Reasonable-cause abatement

The IRS doctrine under which a taxpayer can request abatement of penalties by showing they exercised ordinary business care and prudence but still couldn't meet the obligation. The main tool for abating a Form 5472 penalty after a first-year miss.

Also: Resident agent, RA

A person or company with a physical US address designated by a US entity to receive legal and official mail. Every US LLC and corporation must maintain a registered agent in its state of formation.

Also: Reportable transaction

A transaction between the reporting LLC and a related party (such as the foreign owner) that must be disclosed on Form 5472. Includes contributions, distributions, loans, repayments, services, and expenses paid by one party for the other.

Also: SMLLC

A US limited liability company with exactly one member (owner). By default taxed as a disregarded entity for US federal income tax; this is the entity type most non-US founders use when operating a US company.

Also: Social Security Number

A nine-digit number issued by the US Social Security Administration to US citizens, lawful permanent residents, and some non-residents authorised to work in the US. Not usually relevant to a non-US owner of a US LLC.

Also: Income tax treaty, DTAA

A bilateral agreement between the US and another country that allocates taxing rights between the two jurisdictions. Determines reduced withholding rates, tie-breaker residency rules, and permanent-establishment thresholds for cross-border fact patterns.

Also: Unique Taxpayer Reference

The UK's ten-digit tax identification number for individuals and businesses, issued by HMRC. Used by UK-resident owners as the foreign tax ID on Form 5472.

Also: Certificate of Foreign Status of Beneficial Owner

The IRS form a non-US person provides to a US payer to certify foreign status and (optionally) claim a US tax treaty benefit that reduces withholding on US-source payments.