How to Check a Holiday Date Against the Official Source
Holiday data looks simple and fails quietly. One aggregator copies another, a date moves by decree, and the wrong day propagates into payroll systems for years.
Step 1: find who publishes the date
Every country has one authority. In the United States it is the Office of Personnel Management for federal holidays. Germany splits the job across 16 state governments. China uses a single State Council notice per year. If a dataset cannot name its authority, treat it as a draft.
Step 2: read the current year notice, not last year's
Dates move. Governments add one-off holidays for coronations, elections and mourning, and drop them again the next year. The notice for the year you are planning is the only version that counts.
Step 3: separate the holiday from the observance
- The statutory date, such as 4 July in the United States.
- The observed day off, which was Friday 3 July in 2026 because the 4th fell on a Saturday.
- The closure that actually affects you: banks, courts, schools and private offices each follow their own subset.
Step 4: cross-check one sample date per country
Pick the holiday most likely to have moved, usually the one nearest a weekend, and compare the aggregator against the official notice. One mismatch is a warning. Two means the whole country list needs rebuilding, which is how the tables on this site were assembled from the Nager.Date compilation and its government sources.