™If cost basis appears in a quote, filing or account screen, read it together with the instrument, timeframe and calculation method.
Taxes & Account Rules
Cost basis
The value used to calculate a taxable gain or loss, generally adjusted for certain transactions and events.
Plain-English context
Why it matters
This term is part of the language used to describe ownership, pricing, transactions and investment outcomes.
Assuming Cost basis has one universal interpretation without checking the source, rules, timeframe or methodology.
Use current definitions. Product terms, tax treatment and market rules can change. Confirm important details with official disclosures, regulators and regulated providers.