diff --git a/frontend/src/helpers/time/smartFillStart.test.ts b/frontend/src/helpers/time/smartFillStart.test.ts
index e623125cf..e48caf130 100644
--- a/frontend/src/helpers/time/smartFillStart.test.ts
+++ b/frontend/src/helpers/time/smartFillStart.test.ts
@@ -44,4 +44,14 @@ describe('smartFillStart', () => {
 	it('falls back to 09:00 when no default is configured', () => {
 		expect(smartFillStart([], '', now)).toEqual(new Date('2026-06-07T09:00:00'))
 	})
+
+	it('caps the default start at now when it would be in the future (before 09:00)', () => {
+		const beforeNine = new Date('2026-06-07T07:30:00')
+		expect(smartFillStart([], '09:00', beforeNine)).toEqual(beforeNine)
+	})
+
+	it('caps a future last-entry end at now', () => {
+		const entries = [entry(new Date('2026-06-07T16:00:00'), new Date('2026-06-07T17:00:00'))]
+		expect(smartFillStart(entries, '09:00', now)).toEqual(now)
+	})
 })
diff --git a/frontend/src/helpers/time/smartFillStart.ts b/frontend/src/helpers/time/smartFillStart.ts
index c131c1d0e..0a84a7eea 100644
--- a/frontend/src/helpers/time/smartFillStart.ts
+++ b/frontend/src/helpers/time/smartFillStart.ts
@@ -5,16 +5,20 @@ import type {ITimeEntry} from '@/modelTypes/ITimeEntry'
 // continue from, fall back to the user's configured default start (HH:MM) on
 // the given day.
 export function smartFillStart(recentEntries: ITimeEntry[], defaultStart: string, now: Date): Date {
+	// The filled range ends at now, so a start after now would be inverted (and
+	// rejected on save). Cap at now — e.g. the 09:00 fallback before 9am.
+	const cap = (start: Date) => (start.getTime() > now.getTime() ? new Date(now) : start)
+
 	const lastEnd = recentEntries
 		.map(entry => entry.endTime)
 		.filter((end): end is Date => end !== null)
 		.sort((a, b) => b.getTime() - a.getTime())[0]
 	if (lastEnd !== undefined) {
-		return new Date(lastEnd)
+		return cap(new Date(lastEnd))
 	}
 
 	const [hours, minutes] = (defaultStart || '09:00').split(':').map(Number)
 	const start = new Date(now)
 	start.setHours(hours || 0, minutes || 0, 0, 0)
-	return start
+	return cap(start)
 }