diff --git a/x-pack/plugins/alerts/server/task_runner/task_runner.test.ts b/x-pack/plugins/alerts/server/task_runner/task_runner.test.ts
index d9af3d0ae6d5b..8e345d6ff66a8 100644
--- a/x-pack/plugins/alerts/server/task_runner/task_runner.test.ts
+++ b/x-pack/plugins/alerts/server/task_runner/task_runner.test.ts
@@ -621,9 +621,7 @@ describe('Task Runner', () => {
     expect(await taskRunner.run()).toMatchInlineSnapshot(`
       Object {
         "runAt": 1970-01-01T00:00:10.000Z,
-        "state": Object {
-          "previousStartedAt": 1970-01-01T00:00:00.000Z,
-        },
+        "state": Object {},
       }
     `);
     expect(taskRunnerFactoryInitializerParams.logger.error).toHaveBeenCalledWith(
@@ -727,9 +725,7 @@ describe('Task Runner', () => {
     expect(runnerResult).toMatchInlineSnapshot(`
       Object {
         "runAt": 1970-01-01T00:00:10.000Z,
-        "state": Object {
-          "previousStartedAt": 1970-01-01T00:00:00.000Z,
-        },
+        "state": Object {},
       }
     `);
 
@@ -781,9 +777,7 @@ describe('Task Runner', () => {
     expect(runnerResult).toMatchInlineSnapshot(`
       Object {
         "runAt": 1970-01-01T00:05:00.000Z,
-        "state": Object {
-          "previousStartedAt": 1970-01-01T00:00:00.000Z,
-        },
+        "state": Object {},
       }
     `);
   });
@@ -814,9 +808,7 @@ describe('Task Runner', () => {
     expect(runnerResult).toMatchInlineSnapshot(`
       Object {
         "runAt": 1970-01-01T00:05:00.000Z,
-        "state": Object {
-          "previousStartedAt": 1970-01-01T00:00:00.000Z,
-        },
+        "state": Object {},
       }
     `);
   });
@@ -846,13 +838,48 @@ describe('Task Runner', () => {
     expect(runnerResult).toMatchInlineSnapshot(`
       Object {
         "runAt": 1970-01-01T00:05:00.000Z,
-        "state": Object {
-          "previousStartedAt": 1970-01-01T00:00:00.000Z,
-        },
+        "state": Object {},
       }
     `);
   });
 
+  test(`doesn't change previousStartedAt when it fails to run`, async () => {
+    const originalAlertSate = {
+      previousStartedAt: '1970-01-05T00:00:00.000Z',
+    };
+
+    alertType.executor.mockImplementation(
+      ({ services: executorServices }: AlertExecutorOptions) => {
+        throw new Error('OMG');
+      }
+    );
+
+    const taskRunner = new TaskRunner(
+      alertType,
+      {
+        ...mockedTaskInstance,
+        state: originalAlertSate,
+      },
+      taskRunnerFactoryInitializerParams
+    );
+
+    alertsClient.get.mockResolvedValueOnce(mockedAlertTypeSavedObject);
+    encryptedSavedObjectsClient.getDecryptedAsInternalUser.mockResolvedValueOnce({
+      id: '1',
+      type: 'alert',
+      attributes: {
+        apiKey: Buffer.from('123:abc').toString('base64'),
+      },
+      references: [],
+    });
+
+    const runnerResult = await taskRunner.run();
+
+    expect(runnerResult.state.previousStartedAt).toEqual(
+      new Date(originalAlertSate.previousStartedAt)
+    );
+  });
+
   test('avoids rescheduling a failed Alert Task Runner when it throws due to failing to fetch the alert', async () => {
     alertsClient.get.mockImplementation(() => {
       throw SavedObjectsErrorHelpers.createGenericNotFoundError('task', '1');
@@ -878,9 +905,7 @@ describe('Task Runner', () => {
     expect(runnerResult).toMatchInlineSnapshot(`
       Object {
         "runAt": undefined,
-        "state": Object {
-          "previousStartedAt": 1970-01-01T00:00:00.000Z,
-        },
+        "state": Object {},
       }
     `);
   });
diff --git a/x-pack/plugins/alerts/server/task_runner/task_runner.ts b/x-pack/plugins/alerts/server/task_runner/task_runner.ts
index 1ccf14a3a5334..7da16717aef9f 100644
--- a/x-pack/plugins/alerts/server/task_runner/task_runner.ts
+++ b/x-pack/plugins/alerts/server/task_runner/task_runner.ts
@@ -322,7 +322,7 @@ export class TaskRunner {
   async run(): Promise<AlertTaskRunResult> {
     const {
       params: { alertId, spaceId },
-      startedAt: previousStartedAt,
+      startedAt,
       state: originalState,
     } = this.taskInstance;
 
@@ -360,7 +360,7 @@ export class TaskRunner {
         (stateUpdates: AlertTaskState) => {
           return {
             ...stateUpdates,
-            previousStartedAt,
+            previousStartedAt: startedAt,
           };
         },
         (err: Error) => {
@@ -370,10 +370,7 @@ export class TaskRunner {
           } else {
             this.logger.error(message);
           }
-          return {
-            ...originalState,
-            previousStartedAt,
-          };
+          return originalState;
         }
       ),
       runAt: resolveErr<Date | undefined, Error>(runAt, (err) => {