§481 adjustment

12-month rule

Accounting method

Accounting period

All-events test

Allowance method

Arm’s-length amount

Direct write-off method

Economic performance test

First-in, first-out (FIFO) method

Fiscal year

Flow-through entities

Gross receipts test

Impermissible accounting method

Last-in, first-out (LIFO) method

Mixed-motive expenditures

Ordinary and necessary

Payment liabilities

Permissible accounting method

Personal expenses

Reasonable in amount

Recurring item

Specific identification method

Tax year

Travel expenses

Uniform cost capitalization (UNICAP) rules