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+---
+epic: 4
+story: 4.4
+title: "Business Day Calculations"
+status: draft
+---
+
+## Epic 4 — Date, Time & Time Zones
+**Goal:** Full date/time math, business day calculations, and timezone awareness.
+
+### Story 4.4: Business Day Calculations
+
+As a CalcPad user,
+I want to calculate dates by business days (skipping weekends and optionally holidays),
+So that I can compute deadlines and delivery dates in a work context.
+
+**Acceptance Criteria:**
+
+**Given** the expression `10 business days from today`
+**When** the engine evaluates it on a Monday
+**Then** it returns the date two weeks from today (skipping two weekends)
+
+**Given** the expression `10 business days from today`
+**When** the engine evaluates it on a Wednesday
+**Then** it counts forward 10 weekdays, correctly skipping Saturday and Sunday
+**And** the result is the Wednesday of the following week plus the remaining days
+
+**Given** the expression `5 business days from Friday`
+**When** the engine evaluates it
+**Then** it starts counting from the next Monday (skipping the weekend)
+**And** the result is the following Friday
+
+**Given** a holiday calendar is configured for the US locale
+**When** the expression `3 business days from December 23, 2025` is evaluated
+**Then** it skips December 25 (Christmas) in addition to weekends
+**And** the result reflects the correct business day
+
+**Given** no holiday calendar is configured
+**When** business day calculations are performed
+**Then** only weekends (Saturday and Sunday) are skipped
+**And** all other days are treated as business days
+
+**Given** the expression `today - 5 business days`
+**When** the engine evaluates it
+**Then** it counts backward, skipping weekends
+**And** the result is the correct past business date