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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 | Unit | 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) orPOSTwith 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, toolcheck_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.