Homechevron_rightStandardschevron_rightISO 8601-1:2019 / ISO 8601-2:2019

ActiveInternational Standardupdate Standard Updated: February 2019fact_check Fact checked: Jun 28, 2026

ISO 8601-1:2019 / ISO 8601-2:2019

Date and time — Representations for information interchange

apartmentPublishing Organization:International Organization for Standardization (ISO)

Global Technology Finance & Banking Government Healthcare Logistics & Transportation Services

Standard Introduction

ISO 8601-1:2019 / ISO 8601-2:2019 is an active standard published by International Organization for Standardization (ISO). It is commonly used across Technology, Finance & Banking, Government, Healthcare, Logistics & Transportation, Services and applies in Global.

Use this page to review the official documentation, current status, and the certification or assessment bodies most commonly associated with ISO 8601-1:2019 / ISO 8601-2:2019.

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Unambiguous Date-Time Strings

Defines machine-readable representations for Gregorian dates, 24-hour times, UTC offsets, durations, and intervals used in information interchange.

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Cross-Border Consistency

Reduces ambiguity across locales, time zones, APIs, logs, contracts, healthcare records, financial messages, and regulatory reporting.

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Advanced Extensions

ISO 8601-2 adds extended representations for uncertain, approximate, seasonal, recurring, and grouped date-time values.

list_alt Date-Time Representation Controls

Calendar date, ordinal date, and week date formats
Local time and UTC offset representation
Combined date-time strings for APIs and logs
Duration and time interval expressions
Recurring time intervals
Uncertain or approximate date extensions
Validation rules for data exchange and storage

Who Needs to Comply?

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Software teams, API designers, data-platform teams, financial institutions, healthcare systems, logistics providers, government agencies, analytics teams, and any organization exchanging time-sensitive data across regions or systems.

Key Requirements

Standardize Date-Time Formats

Define the ISO 8601 representations used for APIs, databases, logs, documents, integrations, reports, and user-facing exports.

Preserve Time Zone Meaning

Record UTC offsets or UTC-normalized values where timing matters, and document how local time, daylight saving time, and time zones are handled.

Validate Inputs and Outputs

Apply validation rules so integrations accept expected representations and reject ambiguous or locale-dependent strings.

Govern Legacy Migration

Map existing regional or vendor-specific date formats to ISO 8601, with conversion tests and rollback rules for high-risk systems.

Handle Intervals and Uncertainty

Use the appropriate part of ISO 8601 when systems need durations, intervals, recurring dates, approximate dates, or uncertain dates.

Penalties & Enforcement

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ISO 8601 has no direct penalties. Non-standard date-time formats can still cause production defects, missed deadlines, audit-trail gaps, incorrect retention calculations, payment or trading errors, medical record ambiguity, and regulatory reporting defects.