
Corporate tax is imposed in the United States at the federal, most state, and some local levels on the income of entities treated for tax purposes as corporations. Since January 1, 2018, the nominal federal corporate tax rate in the United States of America is a flat 21% due to the passage of the Tax Cuts and Jobs Act of 2017. State and local taxes and rules vary by jurisdiction, though many are based on federal concepts and definitions. Taxable income may differ from book income both as to timing of income and tax deductions and as to what is taxable. The corporate Alternative Minimum Tax was also eliminated by the 2017 reform, but some states have alternative taxes. Like individuals, corporations must file tax returns every year. They must make quarterly estimated tax payments. Groups of corporations controlled by the same owners may file a consolidated return.

Oregon Ballot Measure 97 was a ballot measure in the 2016 election in the U.S. state of Oregon. The initiative asked voters to determine whether or not to impose a 2.5 percent gross receipts tax on C corporations with Oregon sales exceeding $25 million. S corporations and benefit companies would be exempt from the tax. It was estimated the measure would raise $3 billion annually for the state, if passed.
Base erosion and profit shifting (BEPS) refers to corporate tax planning strategies used by multinationals to "shift" profits from higher-tax jurisdictions to lower-tax jurisdictions, thus "eroding" the "tax-base" of the higher-tax jurisdictions. The Organisation for Economic Co-operation and Development (OECD) define BEPS strategies as "exploiting gaps and mismatches in tax rules".

A basis of accounting is the time various financial transactions are recorded. The cash basis and the accrual basis are the two primary methods of tracking income and expenses in accounting.

A C corporation, under United States federal income tax law, is any corporation that is taxed separately from its owners. A C corporation is distinguished from an S corporation, which generally is not taxed separately. Many companies, including most major corporations, are treated as C corporations for U.S. federal income tax purposes. C corporations and S corporations both enjoy limited liability, but only C corporations are subject to corporate income taxation.

The Double Irish was a base erosion and profit shifting (BEPS) corporate tax tool used mostly by US multinationals since the late 1980s to avoid corporate taxation on non-U.S. profits. It was the largest tax avoidance tool in history and by 2010 was shielding US$100 billion annually in US multinational foreign profits from taxation, and was the main tool by which US multinationals built up untaxed offshore reserves of US$1 trillion from 2004 to 2018. Traditionally, it was also used with the Dutch Sandwich BEPS tool; however, changes to Irish tax law in 2010 dispensed with this requirement.

A low-profit limited liability company (L3C) is a legal form of business entity in the United States. Commonly referred to as a hybrid structure, it has characteristics of both for-profit and non-profit entities. L3Cs were created to comply with the Internal Revenue Service (IRS) program-related investments (PRIs) rules which allow most typically private foundations the ability to maintain tax-exempt status through investments in qualifying businesses and/or charities. With a social mission as the primary objective and a secondary objective of profit generation, the L3C legal form is considered a viable option for businesses seeking a reputation or marketability for being a social enterprise.

Leprechaun economics is a satirical term coined by economist Paul Krugman to describe the 26.3 per cent rise in Irish 2015 GDP, later revised to 34.4 per cent, in a 12 July 2016 publication by the Irish Central Statistics Office (CSO), restating 2015 Irish national accounts. At that point, the historical distortion of Irish economic data by tax-driven accounting flows reached a climax. By 2020, Krugman said the term was a feature of all tax havens.

A limited liability company (LLC) is the US-specific form of a private limited company. It is a business structure that can combine the pass-through taxation of a partnership or sole proprietorship with the limited liability of a corporation. An LLC is not a corporation under state law; it is a legal form of a company that provides limited liability to its owners in many jurisdictions. LLCs are well known for the flexibility that they provide to business owners; depending on the situation, an LLC may elect to use corporate tax rules instead of being treated as a partnership, and, under certain circumstances, LLCs may be organized as not-for-profit. In certain U.S. states, businesses that provide professional services requiring a state professional license, such as legal or medical services, may not be allowed to form an LLC but may be required to form a similar entity called a professional limited liability company (PLLC).

Matheson, is an Irish law firm partnership based in the IFSC in Dublin, which specialises in multinational tax schemes, and tax structuring of special purpose vehicles. Matheson is estimated to be Ireland's largest corporate law firm. Matheson state in the International Tax Review that their tax department is: "significantly the largest tax practice group amongst Irish law firms".

An S corporation, for United States federal income tax, is a closely held corporation that makes a valid election to be taxed under Subchapter S of Chapter 1 of the Internal Revenue Code. In general, S corporations do not pay any income taxes. Instead, the corporation's income and losses are divided among and passed through to its shareholders. The shareholders must then report the income or loss on their own individual income tax returns.

A series limited liability company, commonly known as a series LLC and sometimes abbreviated as SLLC, is a form of a limited liability company that provides liability protection across multiple "series" each of which is theoretically protected from liabilities arising from the other series. In overall structure, the series LLC has been described as a master LLC that has separate divisions, which is similar to an S corporation with Q-subs.

A tax inversion or corporate tax inversion is a form of tax avoidance where a corporation restructures so that the current parent is replaced by a foreign parent, and the original parent company becomes a subsidiary of the foreign parent, thus moving its tax residence to the foreign country. Executives and operational headquarters can stay in the original country. The US definition requires that the original shareholders remain a majority control of the post-inverted company.