Lookback period
In accounting, lookback period means the four quarters — July 1 two years back to June 30 last year — whose Form 941 tax decides a year's deposit schedule: $50,000 or less, monthly; more, semiweekly. A new employer's lookback quarters count as zero.
Authority: IRS Pub. 15 (2026), §11 (opens in a new tab). Sources
The lesson that teaches this
From the free founder back-office course, taught on one company's books, with exercises to work it yourself.
For founders
The same idea written for a founder: what it costs a startup that ignores it, and what to do in a real month.
What it is not called
Each of these means something else. Use one here and an accountant reading the product notices.
- the prior year
- the last four quarters
Components that render the terms it depends on
No component names this concept outright, but it's built from terms that components do name. These render period.
4Swaps & FX
Family spec5Ledger & tables
Family spec- PeriodPickerFiscal-aware. Never assumes January.
- FluxAnalysisPeriod-over-period explanations.
- ProfitAndLossP&L with period comparison and variance.
- ReportHeaderEntity, statement, period, basis, currency, as-of. Every figure states its basis.
- StatementTableThe shared shell: hierarchy, periods, rules.
- StatementToolbarBasis, period, comparison, currency, consolidation.
9Accounting core (GL)
Family spec11Payables (AP)
Family spec12Close, controls & consolidation
Family specAlso in Payroll
Defined in Lexicon. This page is generated from that document, so the two can't disagree.