diff --git a/src/db.ts b/src/db.ts
index 08e827b..a418f78 100644
--- a/src/db.ts
+++ b/src/db.ts
@@ -22,6 +22,12 @@ if (isNewDb) {
   db.exec(schema);
 }
 
+// Lightweight migration for DBs created before internal_note existed on customers.
+const customerColumns = db.prepare(`PRAGMA table_info(customers)`).all() as { name: string }[];
+if (!customerColumns.some((c) => c.name === 'internal_note')) {
+  db.exec(`ALTER TABLE customers ADD COLUMN internal_note TEXT`);
+}
+
 const FIRST_ORDER_NUMBER = 8246;
 
 /** Allocates the next order number inside the caller's transaction. */
diff --git a/src/routes/customers.ts b/src/routes/customers.ts
index 5845207..2916419 100644
--- a/src/routes/customers.ts
+++ b/src/routes/customers.ts
@@ -36,7 +36,7 @@ router.post('/:id/edit', (req, res) => {
     .prepare(
       `UPDATE customers SET
          name = ?, phone = ?, alt_phone = ?, email = ?,
-         address_line1 = ?, address_line2 = ?, city = ?, state = ?, zip = ?
+         address_line1 = ?, address_line2 = ?, city = ?, state = ?, zip = ?, internal_note = ?
        WHERE id = ?`
     )
     .run(
@@ -49,6 +49,7 @@ router.post('/:id/edit', (req, res) => {
       b.city || null,
       b.state || null,
       b.zip || null,
+      b.internal_note || null,
       req.params.id
     );
 
diff --git a/src/schema.sql b/src/schema.sql
index cee5af7..4e7f81a 100644
--- a/src/schema.sql
+++ b/src/schema.sql
@@ -9,6 +9,7 @@ CREATE TABLE customers (
     phone         TEXT,
     alt_phone     TEXT,
     email         TEXT,
+    internal_note TEXT,                             -- staff-only; never printed on the invoice
     created_at    TEXT DEFAULT (datetime('now'))
 );
 
diff --git a/src/views/customers/edit.njk b/src/views/customers/edit.njk
index 370e1c7..b0fa64e 100644
--- a/src/views/customers/edit.njk
+++ b/src/views/customers/edit.njk
@@ -19,6 +19,11 @@
         <label>State <input type="text" name="state" value="{{ customer.state or '' }}"></label>
         <label>Zip <input type="text" name="zip" value="{{ customer.zip or '' }}"></label>
       </div>
+
+      <label>
+        Note <span class="hint">(internal only — never printed on the invoice)</span>
+        <textarea name="internal_note" rows="3">{{ customer.internal_note or '' }}</textarea>
+      </label>
     </fieldset>
 
     <button type="submit">Save</button>