diff --git a/apps/api/src/jobs/__tests__/import-processor.test.ts b/apps/api/src/jobs/__tests__/import-processor.test.ts
index b246699..05381ea 100644
--- a/apps/api/src/jobs/__tests__/import-processor.test.ts
+++ b/apps/api/src/jobs/__tests__/import-processor.test.ts
@@ -1,6 +1,7 @@
 import {beforeEach, describe, expect, it} from 'vitest';
 import {factories, getPrismaClient} from '../../../../../test/helpers';
 import {ContactService} from '../../services/ContactService.js';
+import {coerceCustomValue} from '../import-processor.js';
 
 /**
  * Tests for Contact Import Processor - Subscription Status Preservation
@@ -279,3 +280,25 @@ describe('Contact Import - Subscription Status Preservation', () => {
     });
   });
 });
+
+describe('coerceCustomValue', () => {
+  describe('boolean coercion', () => {
+    it.each(['true', 'TRUE', 'True', ' true ', '1', 'yes', 'YES', 'Yes'])('coerces %j to true', value => {
+      expect(coerceCustomValue(value)).toBe(true);
+    });
+
+    it.each(['false', 'FALSE', 'False', ' false ', '0', 'no', 'NO', 'No'])('coerces %j to false', value => {
+      expect(coerceCustomValue(value)).toBe(false);
+    });
+  });
+
+  describe('passthrough', () => {
+    it.each(['Alice', 'true!', 'yesno', 'maybe', '42', '3.14', '01234'])('leaves %j as a string', value => {
+      expect(coerceCustomValue(value)).toBe(value);
+    });
+
+    it('leaves empty string as empty string', () => {
+      expect(coerceCustomValue('')).toBe('');
+    });
+  });
+});
diff --git a/apps/api/src/jobs/import-processor.ts b/apps/api/src/jobs/import-processor.ts
index f98ccea..ef38fd4 100644
--- a/apps/api/src/jobs/import-processor.ts
+++ b/apps/api/src/jobs/import-processor.ts
@@ -123,7 +123,11 @@ export function createImportWorker() {
 
               // Extract custom data (all fields except email and subscribed)
               const {email: _, subscribed: __, ...customData} = record;
-              const data = Object.keys(customData).length > 0 ? customData : undefined;
+              const customEntries = Object.entries(customData);
+              const data =
+                customEntries.length > 0
+                  ? Object.fromEntries(customEntries.map(([k, v]) => [k, coerceCustomValue(v)]))
+                  : undefined;
 
               // Check if contact exists before upserting
               const existingContact = await ContactService.findByEmail(projectId, email);
@@ -216,3 +220,19 @@ function isValidEmail(email: string): boolean {
   const emailRegex = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;
   return emailRegex.test(email);
 }
+
+const BOOLEAN_TRUE = new Set(['true', '1', 'yes']);
+const BOOLEAN_FALSE = new Set(['false', '0', 'no']);
+
+/**
+ * Coerce a raw CSV cell to its natural JSON primitive so post-import type
+ * inference (ContactService.getAvailableFields) can detect booleans on custom
+ * fields the same way it already does for the reserved `subscribed` column.
+ * Values outside the recognised keyword set are returned unchanged.
+ */
+export function coerceCustomValue(value: string): string | boolean {
+  const lower = value.trim().toLowerCase();
+  if (BOOLEAN_TRUE.has(lower)) return true;
+  if (BOOLEAN_FALSE.has(lower)) return false;
+  return value;
+}