diff --git a/README.md b/README.md
index 7b6a444..d27f5e4 100644
--- a/README.md
+++ b/README.md
@@ -49,6 +49,9 @@ remindctl list Projects --create
 
 remindctl add "Buy milk"
 remindctl add --title "Call mom" --list Personal --due tomorrow
+remindctl add "Plan trip" --due "2026-03-06"          # all-day
+remindctl add "Doctor" --due "2026-03-06 15:00"       # timed
+remindctl add "Holiday" --due "2026-03-06" --all-day  # force all-day
 remindctl edit 1 --title "New title" --due 2026-01-04
 remindctl complete 1 2 3
 remindctl delete 4A83 --force
@@ -68,6 +71,9 @@ Accepted by `--due` and filters:
 - `YYYY-MM-DD HH:mm`
 - ISO 8601 (`2026-01-03T12:34:56Z`)
 
+For `add`, date-only values (for example `2026-03-06`) create all-day reminders.
+Use `--all-day` to explicitly force all-day behavior when setting `--due`.
+
 ## Permissions
 Run `remindctl authorize` to trigger the system prompt. If access is denied, enable
 Terminal (or remindctl) in System Settings → Privacy & Security → Reminders.
diff --git a/Sources/RemindCore/DateParsing.swift b/Sources/RemindCore/DateParsing.swift
index b3be087..7cbf3d3 100644
--- a/Sources/RemindCore/DateParsing.swift
+++ b/Sources/RemindCore/DateParsing.swift
@@ -29,13 +29,13 @@ public enum DateParsing {
     return nil
   }
 
-  public static func formatDisplay(_ date: Date, calendar: Calendar = .current) -> String {
+  public static func formatDisplay(_ date: Date, isAllDay: Bool = false, calendar: Calendar = .current) -> String {
     let formatter = DateFormatter()
     formatter.locale = Locale.current
     formatter.timeZone = calendar.timeZone
     formatter.dateStyle = .medium
-    formatter.timeStyle = .short
-    return formatter.string(from: date)
+    formatter.timeStyle = isAllDay ? .none : .short
+    return isAllDay ? "\(formatter.string(from: date)) (all day)" : formatter.string(from: date)
   }
 
   private static func parseRelativeDate(_ input: String, now: Date, calendar: Calendar) -> Date? {
diff --git a/Sources/RemindCore/EventKitStore.swift b/Sources/RemindCore/EventKitStore.swift
index e44dc89..9cff0e5 100644
--- a/Sources/RemindCore/EventKitStore.swift
+++ b/Sources/RemindCore/EventKitStore.swift
@@ -101,7 +101,7 @@ public actor RemindersStore {
     reminder.calendar = calendar
     reminder.priority = draft.priority.eventKitValue
     if let dueDate = draft.dueDate {
-      reminder.dueDateComponents = calendarComponents(from: dueDate)
+      reminder.dueDateComponents = calendarComponents(from: dueDate, isAllDay: draft.dueDateIsAllDay)
     }
     try eventStore.save(reminder, commit: true)
     return ReminderItem(
@@ -112,6 +112,7 @@ public actor RemindersStore {
       completionDate: reminder.completionDate,
       priority: ReminderPriority(eventKitValue: Int(reminder.priority)),
       dueDate: date(from: reminder.dueDateComponents),
+      dueDateIsAllDay: isAllDay(reminder.dueDateComponents),
       listID: reminder.calendar.calendarIdentifier,
       listName: reminder.calendar.title
     )
@@ -153,6 +154,7 @@ public actor RemindersStore {
       completionDate: reminder.completionDate,
       priority: ReminderPriority(eventKitValue: Int(reminder.priority)),
       dueDate: date(from: reminder.dueDateComponents),
+      dueDateIsAllDay: isAllDay(reminder.dueDateComponents),
       listID: reminder.calendar.calendarIdentifier,
       listName: reminder.calendar.title
     )
@@ -173,6 +175,7 @@ public actor RemindersStore {
           completionDate: reminder.completionDate,
           priority: ReminderPriority(eventKitValue: Int(reminder.priority)),
           dueDate: date(from: reminder.dueDateComponents),
+          dueDateIsAllDay: isAllDay(reminder.dueDateComponents),
           listID: reminder.calendar.calendarIdentifier,
           listName: reminder.calendar.title
         )
@@ -212,6 +215,7 @@ public actor RemindersStore {
       let completionDate: Date?
       let priority: Int
       let dueDateComponents: DateComponents?
+      let dueDateIsAllDay: Bool
       let listID: String
       let listName: String
     }
@@ -220,14 +224,17 @@ public actor RemindersStore {
       let predicate = eventStore.predicateForReminders(in: calendars)
       eventStore.fetchReminders(matching: predicate) { reminders in
         let data = (reminders ?? []).map { reminder in
-          ReminderData(
+          let components = reminder.dueDateComponents
+          let allDay = components != nil && components?.hour == nil && components?.minute == nil
+          return ReminderData(
             id: reminder.calendarItemIdentifier,
             title: reminder.title ?? "",
             notes: reminder.notes,
             isCompleted: reminder.isCompleted,
             completionDate: reminder.completionDate,
             priority: Int(reminder.priority),
-            dueDateComponents: reminder.dueDateComponents,
+            dueDateComponents: components,
+            dueDateIsAllDay: allDay,
             listID: reminder.calendar.calendarIdentifier,
             listName: reminder.calendar.title
           )
@@ -245,6 +252,7 @@ public actor RemindersStore {
         completionDate: data.completionDate,
         priority: ReminderPriority(eventKitValue: data.priority),
         dueDate: date(from: data.dueDateComponents),
+        dueDateIsAllDay: data.dueDateIsAllDay,
         listID: data.listID,
         listName: data.listName
       )
@@ -266,8 +274,11 @@ public actor RemindersStore {
     return calendar
   }
 
-  private func calendarComponents(from date: Date) -> DateComponents {
-    calendar.dateComponents([.year, .month, .day, .hour, .minute], from: date)
+  private func calendarComponents(from date: Date, isAllDay: Bool = false) -> DateComponents {
+    if isAllDay {
+      return calendar.dateComponents([.year, .month, .day], from: date)
+    }
+    return calendar.dateComponents([.year, .month, .day, .hour, .minute], from: date)
   }
 
   private func date(from components: DateComponents?) -> Date? {
@@ -275,6 +286,11 @@ public actor RemindersStore {
     return calendar.date(from: components)
   }
 
+  private func isAllDay(_ components: DateComponents?) -> Bool {
+    guard let components else { return false }
+    return components.hour == nil && components.minute == nil
+  }
+
   private func item(from reminder: EKReminder) -> ReminderItem {
     ReminderItem(
       id: reminder.calendarItemIdentifier,
@@ -284,6 +300,7 @@ public actor RemindersStore {
       completionDate: reminder.completionDate,
       priority: ReminderPriority(eventKitValue: Int(reminder.priority)),
       dueDate: date(from: reminder.dueDateComponents),
+      dueDateIsAllDay: isAllDay(reminder.dueDateComponents),
       listID: reminder.calendar.calendarIdentifier,
       listName: reminder.calendar.title
     )
diff --git a/Sources/RemindCore/Models.swift b/Sources/RemindCore/Models.swift
index 5f4fe90..06557d5 100644
--- a/Sources/RemindCore/Models.swift
+++ b/Sources/RemindCore/Models.swift
@@ -51,6 +51,7 @@ public struct ReminderItem: Identifiable, Codable, Sendable, Equatable {
   public let completionDate: Date?
   public let priority: ReminderPriority
   public let dueDate: Date?
+  public let dueDateIsAllDay: Bool
   public let listID: String
   public let listName: String
 
@@ -62,6 +63,7 @@ public struct ReminderItem: Identifiable, Codable, Sendable, Equatable {
     completionDate: Date?,
     priority: ReminderPriority,
     dueDate: Date?,
+    dueDateIsAllDay: Bool = false,
     listID: String,
     listName: String
   ) {
@@ -72,6 +74,7 @@ public struct ReminderItem: Identifiable, Codable, Sendable, Equatable {
     self.completionDate = completionDate
     self.priority = priority
     self.dueDate = dueDate
+    self.dueDateIsAllDay = dueDateIsAllDay
     self.listID = listID
     self.listName = listName
   }
@@ -81,12 +84,20 @@ public struct ReminderDraft: Sendable {
   public let title: String
   public let notes: String?
   public let dueDate: Date?
+  public let dueDateIsAllDay: Bool
   public let priority: ReminderPriority
 
-  public init(title: String, notes: String?, dueDate: Date?, priority: ReminderPriority) {
+  public init(
+    title: String,
+    notes: String?,
+    dueDate: Date?,
+    dueDateIsAllDay: Bool = false,
+    priority: ReminderPriority
+  ) {
     self.title = title
     self.notes = notes
     self.dueDate = dueDate
+    self.dueDateIsAllDay = dueDateIsAllDay
     self.priority = priority
   }
 }
diff --git a/Sources/remindctl/CommandHelpers.swift b/Sources/remindctl/CommandHelpers.swift
index 6323cdd..d88e2c3 100644
--- a/Sources/remindctl/CommandHelpers.swift
+++ b/Sources/remindctl/CommandHelpers.swift
@@ -2,6 +2,11 @@ import Foundation
 import RemindCore
 
 enum CommandHelpers {
+  struct ParsedDueDate {
+    let date: Date
+    let isAllDay: Bool
+  }
+
   static func parsePriority(_ value: String) throws -> ReminderPriority {
     switch value.lowercased() {
     case "none":
@@ -23,4 +28,22 @@ enum CommandHelpers {
     }
     return date
   }
+
+  static func parseAddDueDate(_ value: String, forceAllDay: Bool) throws -> ParsedDueDate {
+    let date = try parseDueDate(value)
+    let isAllDay = forceAllDay || isDateOnlyInput(value)
+    return ParsedDueDate(date: date, isAllDay: isAllDay)
+  }
+
+  private static func isDateOnlyInput(_ value: String) -> Bool {
+    let trimmed = value.trimmingCharacters(in: .whitespacesAndNewlines)
+    let patterns = [
+      #"^\d{4}-\d{2}-\d{2}$"#,
+      #"^\d{1,2}/\d{1,2}/\d{4}$"#,
+      #"^\d{1,2}-\d{1,2}-(\d{2}|\d{4})$"#,
+    ]
+    return patterns.contains { pattern in
+      trimmed.range(of: pattern, options: .regularExpression) != nil
+    }
+  }
 }
diff --git a/Sources/remindctl/Commands/AddCommand.swift b/Sources/remindctl/Commands/AddCommand.swift
index 571bc25..71fe5f9 100644
--- a/Sources/remindctl/Commands/AddCommand.swift
+++ b/Sources/remindctl/Commands/AddCommand.swift
@@ -24,12 +24,16 @@ enum AddCommand {
               help: "none|low|medium|high",
               parsing: .singleValue
             ),
+          ],
+          flags: [
+            .make(label: "allDay", names: [.long("all-day")], help: "Treat --due as an all-day reminder"),
           ]
         )
       ),
       usageExamples: [
         "remindctl add \"Buy milk\"",
         "remindctl add --title \"Call mom\" --list Personal --due tomorrow",
+        "remindctl add \"Plan trip\" --due 2026-03-06 --all-day",
         "remindctl add \"Review docs\" --priority high",
       ]
     ) { values, runtime in
@@ -56,8 +60,13 @@ enum AddCommand {
       let notes = values.option("notes")
       let dueValue = values.option("due")
       let priorityValue = values.option("priority")
+      let allDayFlag = values.flag("allDay")
+
+      if allDayFlag && dueValue == nil {
+        throw RemindCoreError.operationFailed("--all-day requires --due")
+      }
 
-      let dueDate = try dueValue.map(CommandHelpers.parseDueDate)
+      let dueInput = try dueValue.map { try CommandHelpers.parseAddDueDate($0, forceAllDay: allDayFlag) }
       let priority = try priorityValue.map(CommandHelpers.parsePriority) ?? .none
 
       let store = RemindersStore()
@@ -73,7 +82,13 @@ enum AddCommand {
         throw RemindCoreError.operationFailed("No default list found. Specify --list.")
       }
 
-      let draft = ReminderDraft(title: title, notes: notes, dueDate: dueDate, priority: priority)
+      let draft = ReminderDraft(
+        title: title,
+        notes: notes,
+        dueDate: dueInput?.date,
+        dueDateIsAllDay: dueInput?.isAllDay ?? false,
+        priority: priority
+      )
       let reminder = try await store.createReminder(draft, listName: targetList)
       OutputRenderer.printReminder(reminder, format: runtime.outputFormat)
     }
diff --git a/Sources/remindctl/OutputFormatting.swift b/Sources/remindctl/OutputFormatting.swift
index ee85c61..3b57a46 100644
--- a/Sources/remindctl/OutputFormatting.swift
+++ b/Sources/remindctl/OutputFormatting.swift
@@ -50,7 +50,7 @@ enum OutputRenderer {
   static func printReminder(_ reminder: ReminderItem, format: OutputFormat) {
     switch format {
     case .standard:
-      let due = reminder.dueDate.map { DateParsing.formatDisplay($0) } ?? "no due date"
+      let due = reminder.dueDate.map { DateParsing.formatDisplay($0, isAllDay: reminder.dueDateIsAllDay) } ?? "no due date"
       Swift.print("✓ \(reminder.title) [\(reminder.listName)] — \(due)")
     case .plain:
       Swift.print(plainLine(for: reminder))
@@ -96,7 +96,7 @@ enum OutputRenderer {
     }
     for (index, reminder) in sorted.enumerated() {
       let status = reminder.isCompleted ? "x" : " "
-      let due = reminder.dueDate.map { DateParsing.formatDisplay($0) } ?? "no due date"
+      let due = reminder.dueDate.map { DateParsing.formatDisplay($0, isAllDay: reminder.dueDateIsAllDay) } ?? "no due date"
       let priority = reminder.priority == .none ? "" : " priority=\(reminder.priority.rawValue)"
       Swift.print("[\(index + 1)] [\(status)] \(reminder.title) [\(reminder.listName)] — \(due)\(priority)")
     }
diff --git a/Tests/remindctlTests/AddCommandParsingTests.swift b/Tests/remindctlTests/AddCommandParsingTests.swift
new file mode 100644
index 0000000..618d64a
--- /dev/null
+++ b/Tests/remindctlTests/AddCommandParsingTests.swift
@@ -0,0 +1,25 @@
+import Foundation
+import Testing
+
+@testable import remindctl
+
+@MainActor
+struct AddCommandParsingTests {
+  @Test("Date-only due input defaults to all-day")
+  func dateOnlyDueDefaultsToAllDay() throws {
+    let parsed = try CommandHelpers.parseAddDueDate("2026-03-06", forceAllDay: false)
+    #expect(parsed.isAllDay == true)
+  }
+
+  @Test("Date-time due input remains timed")
+  func dateTimeDueRemainsTimed() throws {
+    let parsed = try CommandHelpers.parseAddDueDate("2026-03-06 15:00", forceAllDay: false)
+    #expect(parsed.isAllDay == false)
+  }
+
+  @Test("--all-day forces all-day for due input")
+  func allDayFlagForcesAllDay() throws {
+    let parsed = try CommandHelpers.parseAddDueDate("2026-03-06 15:00", forceAllDay: true)
+    #expect(parsed.isAllDay == true)
+  }
+}