n8n Workflow for Automating Performance Review Reminders in 2026

This workflow reads a Google Sheet containing employee review due dates, calculates how many days remain until each deadline, and automatically sends a personalised reminder email via Gmail and a Slack message to the employee’s manager — 14 days before and again 3 days before the review is due. It replaces a manual Monday-morning calendar check and copy-paste email routine that typically takes 45 minutes per week across a team of 30+ employees.

Why this automation matters

Without this workflow, HR Managers must manually scan a spreadsheet, identify upcoming review deadlines, open Gmail, personalise each message with the employee name and manager, send it, then repeat the process in Slack. One missed lookup means a manager walks into a review cycle unprepared, or an employee submits a self-assessment after the window closes. The two-stage reminder cadence (14 days and 3 days out) mirrors what most HR teams already do manually — this workflow just executes it without human intervention every Monday at 8 AM.

What you need before starting

Google Sheets OAuth2 credential connected to the Google account that owns the performance review tracker sheet.
Gmail OAuth2 credential connected to the HR team inbox that sends review reminders (e.g. hr@yourcompany.com).
Slack API credential (Bot Token with chat:write scope) for the Slack workspace where manager channels or DMs exist.
A Google Sheet named Performance Review Tracker with the following exact column headers in row 1: Employee Name, Employee Email, Manager Name, Manager Email, Manager Slack ID, Review Due Date (formatted as YYYY-MM-DD), Status (values: Pending, Complete).
n8n instance running on n8n Cloud (https://n8n.io/) or self-hosted v1.40 or later.
The Date & Time and IF nodes are built into n8n — no additional installation required.

How to build it: step by step

1. Schedule Trigger — Run every Monday at 8 AM

Node type: Schedule Trigger Field: Trigger Interval → set to Weeks Field: Week Interval → 1 Field: Trigger on Weekdays → Monday Field: Trigger at Hour → 8 Field: Trigger at Minute → 0 Output: Fires once every Monday at 08:00 and passes a single empty item to the next node. Why this matters: Running once weekly is sufficient because review due dates rarely change day-to-day. Running it daily would flood managers with repeated messages.

2. Google Sheets — Read all pending review rows

Node type: Google Sheets Operation: Read Rows Credential: Select your Google Sheets OAuth2 credential Spreadsheet: Performance Review Tracker (select from the dropdown after authentication) Sheet: Sheet1 Filter Rows: Enable → Column: Status | Condition: equals | Value: Pending Output: One item per row where Status is Pending. Each item contains the fields: Employee Name, Employee Email, Manager Name, Manager Email, Manager Slack ID, Review Due Date. Why this matters: Filtering out Complete rows here prevents the workflow from sending reminders for reviews that are already done. If you skip this filter, managers receive reminders after they have already submitted the review.

3. Code — Calculate days until review due date

Node type: Code Language: JavaScript Code to paste:

const items = $input.all();
const today = new Date();
today.setHours(0, 0, 0, 0);

return items.map(item => {
  const dueDate = new Date(item.json['Review Due Date']);
  dueDate.setHours(0, 0, 0, 0);
  const diffMs = dueDate - today;
  const daysUntilDue = Math.round(diffMs / (1000 * 60 * 60 * 24));
  return {
    json: {
      ...item.json,
      daysUntilDue
    }
  };
});

Output: All input items with a new daysUntilDue integer field appended. A value of 14 means the review is due in exactly 14 days. Negative values mean the deadline has passed. Why this matters: n8n has no native “date difference” node. This calculation is the only way to accurately filter who needs a reminder today versus who does not.

4. IF — Filter for 14-day or 3-day reminders only

Node type: IF Condition 1: {{ $json.daysUntilDue }} equals 14 Combine with: OR Condition 2: {{ $json.daysUntilDue }} equals 3 Output (true branch): Items where the review is due in exactly 14 or 3 days. These pass forward to the email and Slack nodes. Output (false branch): All other items. Connect the false branch to a No Operation node to terminate cleanly. Why this matters: Without this filter, every Pending row sends a reminder every Monday regardless of timing. The OR condition is what creates the two-stage cadence.

5. Gmail — Send reminder email to employee

Node type: Gmail Credential: Select your Gmail OAuth2 credential Operation: Send To: {{ $json['Employee Email'] }} Subject: Reminder: Your performance review is due in {{ $json.daysUntilDue }} days Email Type: HTML Body:

<p>Hi {{ $json['Employee Name'] }},</p>
<p>This is a reminder that your performance self-assessment is due on <strong>{{ $json['Review Due Date'] }}</strong> — that's {{ $json.daysUntilDue }} days from today.</p>
<p>Please log in to complete your self-assessment before the deadline. If you have questions, contact the HR team at hr@yourcompany.com.</p>
<p>Thank you,<br>HR Team</p>

Output: One email sent per item. The node outputs the original item with a messageId field added confirming delivery. Why this matters: Using {{ $json['Employee Name'] }} in the body personalises each email without any manual copy-paste. Every employee in the filtered batch receives a unique message in a single execution.

6. Gmail — Send reminder email to manager

Node type: Gmail (add a second Gmail node after node 5) Credential: Select your Gmail OAuth2 credential Operation: Send To: {{ $json['Manager Email'] }} Subject: Action required: {{ $json['Employee Name'] }}'s review is due in {{ $json.daysUntilDue }} days Email Type: HTML Body:

<p>Hi {{ $json['Manager Name'] }},</p>
<p>This is a heads-up that <strong>{{ $json['Employee Name'] }}</strong>'s performance review is due on <strong>{{ $json['Review Due Date'] }}</strong>.</p>
<p>Please ensure you have scheduled the review meeting and completed your manager assessment before the deadline. Contact hr@yourcompany.com with any questions.</p>
<p>HR Team</p>

Output: One email per item sent to the manager’s address. Passes items forward unchanged. Why this matters: Managers and employees get separate emails because the calls to action are different — employees complete a self-assessment, managers complete a review and schedule a meeting.

7. Slack — Send DM to manager

Node type: Slack Credential: Select your Slack API (Bot Token) credential Resource: Message Operation: Post Send Message To: User User: {{ $json['Manager Slack ID'] }} Text:

:calendar: *Performance Review Reminder*
Hi {{ $json['Manager Name'] }}, {{ $json['Employee Name'] }}'s review is due in *{{ $json.daysUntilDue }} days* ({{ $json['Review Due Date'] }}). Please complete your manager assessment and confirm the meeting is booked.

Output: One Slack DM per item sent to the manager’s Slack user ID. Node outputs the original item plus a Slack ts (message timestamp) confirming delivery. Why this matters: Many managers respond faster to a Slack DM than email. The Manager Slack ID field in your sheet must be the Slack member ID (format: U0123ABCDE), not the display name, or the message will fail to deliver.

8. No Operation — Terminate false branch

Node type: No Operation, do nothing Configuration: None required. Connect to: False output of node 4 (IF node). Why this matters: Connecting the false branch prevents n8n from flagging the workflow as having unconnected outputs, which can cause misleading error alerts in some n8n versions.

Full workflow JSON

{
  "name": "Performance Review Reminders",
  "nodes": [
    {
      "parameters": {
        "rule": {
          "interval": [
            {
              "field": "weeks",
              "weeksInterval": 1,
              "triggerAtDay": [1],
              "triggerAtHour": 8,
              "triggerAtMinute": 0
            }
          ]
        }
      },
      "id": "a1b2c3d4-0001-0001-0001-000000000001",
      "name": "Every Monday 8AM",
      "type": "n8n-nodes-base.scheduleTrigger",
      "typeVersion": 1.1,
      "position": [260, 300]
    },
    {
      "parameters": {
        "operation": "readRows",
        "documentId": {
          "__rl": true,
          "value": "YOUR_GOOGLE_SHEET_ID",
          "mode": "id"
        },
        "sheetName": {
          "__rl": true,
          "value": "Sheet1",
          "mode": "name"
        },
        "filtersUI": {
          "values": [
            {
              "lookupColumn": "Status",
              "lookupValue": "Pending"
            }
          ]
        },
        "options": {}
      },
      "id": "a1b2c3d4-0002-0002-0002-000000000002",
      "name": "Read Pending Reviews",
      "type": "n8n-nodes-base.googleSheets",
      "typeVersion": 4.2,
      "position": [480, 300],
      "credentials": {
        "googleSheetsOAuth2Api": {
          "id": "REPLACE_WITH_YOUR_GOOGLE_SHEETS_CREDENTIAL_ID",
          "name": "Google Sheets account"
        }
      }
    },
    {
      "parameters": {
        "jsCode": "const items = $input.all();\nconst today = new Date();\ntoday.setHours(0, 0, 0, 0);\n\nreturn items.map(item => {\n  const dueDate = new Date(item.json['Review Due Date']);\n  dueDate.setHours(0, 0, 0, 0);\n  const diffMs = dueDate - today;\n  const daysUntilDue = Math.round(diffMs / (1000 *