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FDA Warning Letter Response Deadline Calculator

FDA’s Regulatory Procedures Manual describes a Warning Letter response as usually due within 15 working days — a strong norm, not a fixed statutory deadline. Enter the date on your letter (and, if known, the date you actually received it) and this calculator counts working days forward, skipping weekends and US federal holidays, to show you the resulting date.

The response clock is generally counted from receipt, not the printed date. If you know the receipt date, use it here for the more accurate result.

FDA’s Regulatory Procedures Manual default is 15 working days, but a small number of letters have specified a different window (e.g. 30 business days). Check your own letter before relying on the default.

Which federal holidays does this calculator exclude?

This calculator excludes Saturdays, Sundays, and the 2026-2027 US federal holidays listed below (observed dates, shifted to the nearest weekday where the actual date falls on a weekend). It does not exclude any other closures (state holidays, agency furloughs, weather closures, etc.) since those are not fixed, publicly-scheduled dates.

  • 2026-01-01 — New Year's Day
  • 2026-01-19 — Martin Luther King Jr. Day
  • 2026-02-16 — Washington's Birthday (Presidents Day)
  • 2026-05-25 — Memorial Day
  • 2026-06-19 — Juneteenth
  • 2026-07-03 — Independence Day (observed; July 4 falls on a Saturday)
  • 2026-09-07 — Labor Day
  • 2026-10-12 — Columbus Day
  • 2026-11-11 — Veterans Day
  • 2026-11-26 — Thanksgiving Day
  • 2026-12-25 — Christmas Day
  • 2027-01-01 — New Year's Day
  • 2027-01-18 — Martin Luther King Jr. Day
  • 2027-02-15 — Washington's Birthday (Presidents Day)
  • 2027-05-31 — Memorial Day
  • 2027-06-18 — Juneteenth (observed; June 19 falls on a Saturday)
  • 2027-07-05 — Independence Day (observed; July 4 falls on a Sunday)
  • 2027-09-06 — Labor Day
  • 2027-10-11 — Columbus Day
  • 2027-11-11 — Veterans Day
  • 2027-11-25 — Thanksgiving Day
  • 2027-12-24 — Christmas Day (observed; Dec 25 falls on a Saturday)
  • 2027-12-31 — New Year's Day 2028 (observed; Jan 1, 2028 falls on a Saturday)

This is arithmetic, not legal advice. FDA’s Regulatory Procedures Manual describes 15 working days as the usual response window, not a fixed statutory deadline — some letters specify a different number. The date and number stated in your own letter always control over this calculator. See how the FDA Warning Letter response deadline actually works for the full explanation, including the separate Form 483 response clock.

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Looking up a specific letter instead? Search the FDA Warning Letter Lookup. Argus HQ monitors FDA warning letters daily. See plans for ongoing per-company monitoring.