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16 foundational terms

A working tax vocabulary.

Plain-language definitions for the ideas that recur throughout the research library. English terms remain visible across both languages.

Adjusted gross income (AGI)
Gross income after specified adjustments, before the standard or itemized deduction.
Taxable income
The income base remaining after applicable deductions, subject to the rules for the taxpayer and tax year.
Marginal tax rate
The rate applied to an additional slice of income under a specified model. It is not the rate on every dollar.
Effective tax rate
A tax amount divided by a clearly identified income measure. Different denominators produce different comparisons.
Deduction
An amount that reduces an income base when the relevant statutory requirements and limitations are met.
Tax credit
An amount applied against tax, subject to its own eligibility, limits and refundability rules.
Outside basis
The partner’s adjusted tax basis in the partnership interest. It differs from asset basis and capital-account balances.
Inside basis
The partnership’s tax basis in its assets. Each asset can have a separate basis and history.
Book capital
An economic capital-account concept, often studied under § 704(b), distinct from outside tax basis.
Guaranteed payment
A payment for services or use of capital determined without regard to partnership income under § 707(c).
Distributive share
A partner’s allocated share of partnership tax items. An allocation is distinct from receiving cash.
Distribution
Money or property transferred by a partnership to a partner in that capacity, subject to distribution and special rules.
At-risk limitation
A separate loss limitation based on the amounts the taxpayer is treated as having at risk under § 465.
Passive activity
A classification under § 469 whose loss and credit limitations require their own participation and activity analysis.
Federal conformity
Whether and how a state adopts a federal tax rule. A federal change does not automatically settle the state result.
Safe harbor
A rule that provides a defined treatment when its conditions are met. Estimated-tax targets also depend on payment timing.

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