diff --git a/packages/schemas/src/events.ts b/packages/schemas/src/events.ts
index 24793867..90ea5e99 100644
--- a/packages/schemas/src/events.ts
+++ b/packages/schemas/src/events.ts
@@ -6,6 +6,8 @@ import {
 } from "temporal-zod";
 import * as z from "zod";
 
+import { isBefore, isSameType } from "@repo/temporal";
+
 const conferenceEntryPointSchema = z.object({
   joinUrl: z.object({
     label: z.string().optional(),
@@ -205,33 +207,66 @@ export const recurrenceSchema = z
     },
   );
 
-export const createEventInputSchema = z.object({
-  id: z.string(),
-  title: z.string().optional(),
-  start: dateInputSchema,
-  end: dateInputSchema,
-  allDay: z.boolean().optional(),
-  recurrence: recurrenceSchema.optional(),
-  recurringEventId: z.string().optional(),
-  description: z.string().optional(),
-  location: z.string().optional(),
-  availability: z.enum(["busy", "free"]).optional(),
-  color: z.string().optional(),
-  visibility: z
-    .enum(["default", "public", "private", "confidential"])
-    .optional(),
-  accountId: z.string(),
-  calendarId: z.string(),
-  providerId: z.enum(["google", "microsoft"]),
-  readOnly: z.boolean(),
-  metadata: z.union([microsoftMetadataSchema, googleMetadataSchema]).optional(),
-  attendees: z.array(attendeeSchema).optional(),
-  conference: conferenceSchema.optional(),
-  createdAt: z.instanceof(Temporal.Instant).optional(),
-  updatedAt: z.instanceof(Temporal.Instant).optional(),
-});
+export const createEventInputSchema = z
+  .object({
+    id: z.string(),
+    title: z.string().optional(),
+    start: dateInputSchema,
+    end: dateInputSchema,
+    allDay: z.boolean().optional(),
+    recurrence: recurrenceSchema.optional(),
+    recurringEventId: z.string().optional(),
+    description: z.string().optional(),
+    location: z.string().optional(),
+    availability: z.enum(["busy", "free"]).optional(),
+    color: z.string().optional(),
+    visibility: z
+      .enum(["default", "public", "private", "confidential"])
+      .optional(),
+    accountId: z.string(),
+    calendarId: z.string(),
+    providerId: z.enum(["google", "microsoft"]),
+    readOnly: z.boolean(),
+    metadata: z
+      .union([microsoftMetadataSchema, googleMetadataSchema])
+      .optional(),
+    attendees: z.array(attendeeSchema).optional(),
+    conference: conferenceSchema.optional(),
+    createdAt: z.instanceof(Temporal.Instant).optional(),
+    updatedAt: z.instanceof(Temporal.Instant).optional(),
+  })
+  .refine(
+    (data) => {
+      if (!isSameType(data.start, data.end)) {
+        return false;
+      }
+      if (
+        data.start instanceof Temporal.PlainDate &&
+        data.end instanceof Temporal.PlainDate
+      ) {
+        return isBefore(data.start, data.end);
+      }
+      if (
+        data.start instanceof Temporal.Instant &&
+        data.end instanceof Temporal.Instant
+      ) {
+        return isBefore(data.start, data.end);
+      }
+      if (
+        data.start instanceof Temporal.ZonedDateTime &&
+        data.end instanceof Temporal.ZonedDateTime
+      ) {
+        return isBefore(data.start, data.end);
+      }
+      return false;
+    },
+    {
+      message: "Event start time must be earlier than end time",
+      path: ["start"],
+    },
+  );
 
-export const updateEventInputSchema = createEventInputSchema.extend({
+export const updateEventInputSchema = createEventInputSchema.safeExtend({
   id: z.string(),
   etag: z.string().optional(),
   metadata: z.union([microsoftMetadataSchema, googleMetadataSchema]).optional(),
diff --git a/packages/temporal/src/compare.ts b/packages/temporal/src/compare.ts
index c09126f9..f36b9fd7 100644
--- a/packages/temporal/src/compare.ts
+++ b/packages/temporal/src/compare.ts
@@ -286,6 +286,13 @@ export function isToday(
   return today.equals(toPlainDate(value, { timeZone }));
 }
 
+export function isSameType(
+  a: TemporalConvertible,
+  b: TemporalConvertible,
+): boolean {
+  return a.constructor === b.constructor;
+}
+
 export function isBefore(a: Temporal.PlainDate, b: Temporal.PlainDate): boolean;
 export function isBefore(
   a: Temporal.ZonedDateTime,