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 or no-tax locations where there is little or no economic activity, thus "eroding" the "tax-base" of the higher-tax jurisdictions using deductible payments such as interest or royalties. For the government, the tax base is a company's income or profit. Tax is levied as a percentage on this income/profit. When that income / profit is transferred to a tax haven, the tax base is eroded and the company does not pay taxes to the country that is generating the income. As a result, tax revenues are reduced and the country is disadvantaged. The Organisation for Economic Co-operation and Development (OECD) define BEPS strategies as "exploiting gaps and mismatches in tax rules". While some of the tactics are illegal, the majority are not. Because businesses that operate across borders can utilize BEPS to obtain a competitive edge over domestic businesses, it affects the righteousness and integrity of tax systems. Furthermore, it lessens deliberate compliance, when taxpayers notice multinationals legally avoiding corporate income taxes. Because developing nations rely more heavily on corporate income tax, they are disproportionately affected by BEPS.

Tax avoidance is the legal usage of the tax regime in a single territory to one's own advantage to reduce the amount of tax that is payable by means that are within the law. A tax shelter is one type of tax avoidance, and tax havens are jurisdictions that facilitate reduced taxes. Tax avoidance should not be confused with tax evasion, which is illegal. Both tax evasion and tax avoidance can be viewed as forms of tax noncompliance, as they describe a range of activities that intend to subvert a state's tax system.