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Last reviewed: 2026-08-02 Accepted decision: - ../decisions/accepted/0033-company-accounting-time-and-period-cutoffs.md

Business Time Contract

Purpose

This contract distinguishes exact event time, local presentation, source-world business time, and company accounting-period boundaries.

Canonical concepts

  • Instant: one exact point in time, normalized to UTC for persistence and comparison.
  • Named time zone: an IANA time-zone identifier whose rules resolve civil time and the applicable offset for a particular instant.
  • Business date: a DateOnly-equivalent calendar date whose owning context supplies its meaning.
  • Accounting time zone: the company-owned named zone used to resolve its FinancialPeriod timestamp boundaries.
  • Source time zone: the named zone preserved with a source-world local event or cutoff when that provenance affects interpretation.
  • Display time zone: a presentation preference that never changes durable accounting meaning.

Rules

  • Durable timestamps preserve exact instants; storage or transport may normalize them to UTC without changing identity.
  • A named time-zone id is stored instead of a fixed UTC offset. The applicable offset is derived for the instant being presented or resolved.
  • FinancialPeriod dates are inclusive company-local business dates.
  • A period timestamp cutoff is [start, endExclusive), beginning at local midnight on start_date and ending at local midnight immediately after end_date, resolved in the company's accounting time zone.
  • Resolution preserves the accounting time-zone id and resolved UTC instants when the cutoff is persisted, fingerprinted, reconciled, or used as durable control evidence.
  • Invalid, unavailable, or ambiguous local boundaries block timestamp-based selection. Code must not silently use the host time zone, user display zone, source zone, current offset, or UTC as a substitute.
  • A source-world timestamp retains its source zone when local civil time affects business meaning. Its posting date still resolves through the owning workflow and central FinancialPeriod control.
  • User-local rendering and zone changes are presentation behavior. They do not alter source identity, posting date, period membership, reports, close, audit ordering, or historical results.
  • Accounting views distinguish a period or close date from the timestamps of evaluation, approval, finalization, capture, or generation.

Consolidation compatibility

A future consolidation contract may map separately governed company periods into a group reporting period. It must preserve each entity's period identity, accounting time zone, cutoff evidence, and any required reporting-date difference treatment. It must not assign group membership solely from raw UTC timestamp overlap.

Explicitly deferred

  • operational-location master data;
  • per-user display time-zone preferences;
  • group calendars and consolidation-period mapping;
  • currency translation, remeasurement, and elimination policy; and
  • provider-specific time-zone inference.
  • company.contract.md
  • financial-period.contract.md
  • kernel.contract.md
  • inventory-period-summary-fact.contract.md
  • banking-and-finance-summary-fact.contract.md
  • close-run.contract.md
  • reporting.contract.md