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US Federal Holiday Working Day

Checks a date against the OPM federal-employee holiday schedule and the US Saturday/Sunday baseline.

When to use

You need US federal employee or federal-office holiday status for 2026-2027.

Do not use when: You need a state/local/private-employer/exchange calendar or an alternate federal work schedule without explicit in-lieu resolution.

Example user requests

Is 2027-07-05 a US federal working day?

Formula

is_working_day = US weekday baseline and no OPM federal holiday

Apply the pinned OPM observed-date schedule on top of the CLDR US weekend baseline.

Inputs

Parameter	Type	Unit	Required	Description
`date`	date		yes	Gregorian date in the pinned OPM 2026-2027 coverage.

Outputs

Output	Type	Description
`territory`	string	US.
`territory_name`	string	United States.
`weekday`	string	Gregorian weekday.
`is_working_day`	boolean	True when the US Saturday/Sunday baseline is a weekday and no OPM federal holiday applies.
`day_type`	string	Regular weekday, regular weekend or OPM federal holiday.
`holiday_names`	string_list	OPM federal holiday names applying on the date.
`holiday_observed`	boolean	True when the date is the OPM in-lieu/observed date for a holiday whose actual date is a weekend.
`holiday_actual_dates`	string_list	Underlying statutory holiday dates for observed events.
`weekend_days`	string_list	CLDR Saturday/Sunday baseline.
`rest_day_policy`	string	OPM alternative work schedules need separate in-lieu resolution.
`calendar_scope`	string	Federal employees and federal offices only.
`calendar_profile`	string	us-opm-federal-holidays.
`source_quality`	string	Official OPM schedule and federal-law references.
`dataset_version`	string	Pinned OPM evidence package.
`sources`	list	Official OPM, federal guidance and legislation sources.

Example

Observed Independence Day: {"date":"2027-07-05"} → {"is_working_day":false,"holiday_observed":true}

GET https://tttkmbb.com/api/v1/calculate/us-federal-working-day?date=2027-07-05

Machine access

API: GET https://tttkmbb.com/api/v1/calculate/us-federal-working-day (query parameters) or POST with a JSON body {"inputs": {...}}
Schema: https://tttkmbb.com/api/v1/calculators/us-federal-working-day · Markdown: https://tttkmbb.com/everyday/us-federal-working-day.md · JSON definition: https://tttkmbb.com/everyday/us-federal-working-day.json
MCP: server https://tttkmbb.com/mcp, tool check_us_federal_working_day
OpenAPI operationId: check_us_federal_working_day
Freshness: static. Authentication: none. Rate limit: fair use (see rate limits).

Sources

U.S. Office of Personnel Management Federal Holidays (government)
OPM Federal Holidays - In Lieu Of Determination (government_guidance)
5 U.S.C. 6103 (legislation)

FAQ

Does this cover US state holidays?

No. It is limited to OPM federal employees and federal offices.

Related calculators

Add US Federal Working Days — Offset using the same OPM evidence package.