A business day is any weekday that isn’t a federal holiday, but that short answer hides a problem: federal banking rules, consumer lending rules, the Uniform Commercial Code, court rules, and the tax code each define a business day a little differently. So the real question of what a business day is depends on what you’re counting it for. The common ground is that Saturdays, Sundays, and the eleven federal holidays listed in 5 U.S.C. § 6103 usually don’t count. From there, the rules split.
The Federal Holidays That Don’t Count
Almost every federal definition of “business day” excludes the holidays recognized under 5 U.S.C. § 6103:1U.S. Government Publishing Office. 5 USC 6103 – Holidays
- New Year’s Day (January 1)
- Martin Luther King Jr. Day (third Monday in January)
- Washington’s Birthday (third Monday in February)
- Memorial Day (last Monday in May)
- Juneteenth (June 19)
- Independence Day (July 4)
- Labor Day (first Monday in September)
- Columbus Day (second Monday in October)
- Veterans Day (November 11)
- Thanksgiving Day (fourth Thursday in November)
- Christmas Day (December 25)
When a fixed-date holiday like July 4 or Christmas lands on a Saturday, the preceding Friday is observed. When it lands on a Sunday, the following Monday is observed. A deadline that would expire on the observed holiday rolls to the next business day.2Office of the Law Revision Counsel. 5 USC 6103 – Holidays
How to Count a Deadline
Counting depends entirely on the words your deadline uses. “Days,” “business days,” and “calendar days” each produce a different answer.
Deadlines Written in “Days” (The FRCP Method)
Federal Rule of Civil Procedure 6(a) is the model many agencies and contracts follow when a deadline is written in plain “days.” The rule works in two steps. First, you don’t count the day the clock starts. If you receive a notice Tuesday that gives you ten days to respond, Tuesday is day zero and Wednesday is day one.3Cornell Law School. Federal Rules of Civil Procedure Rule 6 – Computing and Extending Time
Second, you count every calendar day in between, weekends and holidays included. The exclusion only applies at the end: if the last day falls on a Saturday, Sunday, or legal holiday, the deadline extends to the next day that isn’t one of those.3Cornell Law School. Federal Rules of Civil Procedure Rule 6 – Computing and Extending Time A ten-day period under this rule is ten calendar days with a safety valve at the end, not ten weekdays.
Deadlines Written in “Business Days”
When a contract or notice specifies “business days,” you skip Saturdays, Sundays, and holidays during the count itself. Five business days starting from a Wednesday means Thursday (1), Friday (2), skip the weekend, Monday (3), Tuesday (4), Wednesday (5). Five business days covers seven calendar days with no holidays in the mix, and more when a holiday falls inside the window.
Read the actual language before you count. A document that says “days” is probably calendar-based with the end-of-period exception. “Business days” gives you the weekends off during the count. Mixing those up is how people miss filings and lose rescission rights.
Where the Definition Shifts
No single federal statute defines “business day” for all purposes. Agencies wrote their own definitions for their own industries, and the version that applies to you depends on what you’re doing.
Banking and Check Deposits
Regulation CC defines a business day as any calendar day except Saturdays, Sundays, and the federal holidays listed in 5 U.S.C. § 6103.4eCFR. 12 CFR 229.2 – Definitions This is the Monday-through-Friday-minus-holidays version most people have in mind.
The Uniform Commercial Code adds a narrower concept, the “banking day,” meaning the portion of any day when a bank is open to the public for substantially all of its banking functions.5Cornell Law School. UCC 4-104 – Definitions and Index of Definitions Banks set cutoff times, often early-to-mid afternoon, and anything received after the cutoff is treated as arriving on the next banking day. A deposit made at 3:00 PM on a Monday may count as a Tuesday deposit for availability purposes, even though the calendar still says Monday.
Consumer Lending and Mortgage Closings
Regulation Z uses two definitions at once. The general definition counts any day the lender is open for substantially all business, so a lender open on Saturdays treats Saturday as a business day. But for mortgage closing disclosures and the right of rescission, Regulation Z switches to a narrower rule: all calendar days except Sundays and the federal holidays in 5 U.S.C. § 6103.6eCFR. 12 CFR 1026.2 – Definitions and Rules of Construction Under this version, Saturdays count as business days. Sundays do not.
This matters for the Closing Disclosure your lender must deliver at least three business days before you finalize a mortgage. A Closing Disclosure delivered on a Wednesday allows closing as early as Saturday. If you receive it Thursday, the earliest closing is the following Monday because Sunday doesn’t count. A federal holiday inside the window pushes the earliest closing another day. If the lender makes certain significant changes to the disclosure, the three-day clock resets from the corrected version.
Tax Filings
The IRS has its own rule under 26 U.S.C. § 7503. When the last day to file a return or make a payment falls on a Saturday, Sunday, or legal holiday, the deadline moves to the next day that isn’t one of those.7Office of the Law Revision Counsel. 26 USC 7503 – Time for Performance of Certain Acts The IRS definition of “legal holiday” also includes holidays observed in Washington, D.C., and, for returns filed at IRS offices outside D.C., statewide holidays in the state where that office sits. The 2026 individual income tax deadline is April 15, which falls on a Wednesday, so no adjustment applies.8Internal Revenue Service. When to File
Online Orders and Shipping
When an online seller advertises shipping in a certain number of business days, the FTC’s Mail, Internet, or Telephone Order Merchandise Rule requires the seller to have a reasonable basis to believe it can meet that timeframe. If no shipping timeframe is stated, the default under the rule is 30 days from receipt of a complete order.9eCFR. 16 CFR Part 435 – Mail, Internet, or Telephone Order Merchandise A seller’s business-day estimate for shipping starts when the package leaves its facility, not when it arrives. Carrier transit time adds more business days.
Why Calendar Days and Business Days Pull Apart
The gap between the two is wider than it looks. Five business days is one workweek but seven calendar days. Ten business days covers two calendar weeks. Add a federal holiday and you’re looking at fifteen or sixteen calendar days to work through ten business ones. That buffer is designed in, but it works against you when you’re waiting for funds, a refund, or a response. When you’re the one facing the deadline, the same buffer can save you — if you’ve read the language carefully enough to know which clock is running.