diff --git a/init.php b/init.php
index 2fd6c48a9c..de7bc53f4b 100644
--- a/init.php
+++ b/init.php
@@ -157,6 +157,7 @@
 // Services
 require __DIR__ . '/lib/Service/AbstractService.php';
 require __DIR__ . '/lib/Service/CouponService.php';
+require __DIR__ . '/lib/Service/CustomerService.php';
 require __DIR__ . '/lib/Service/FileService.php';
 require __DIR__ . '/lib/Service/Issuing/CardService.php';
 require __DIR__ . '/lib/Service/PaymentIntentService.php';
diff --git a/lib/Service/AbstractService.php b/lib/Service/AbstractService.php
index e0311e4d3b..3c43735857 100644
--- a/lib/Service/AbstractService.php
+++ b/lib/Service/AbstractService.php
@@ -45,31 +45,61 @@ protected function allObjects($params, $opts)
         return $this->request('get', $this->basePath(), $params, $opts);
     }
 
+    protected function allNestedObjects($nestedPath, $parentId, $params, $opts)
+    {
+        return $this->request('get', $this->baseNestedPath($parentId, $nestedPath), $params, $opts);
+    }
+
     protected function createObject($params, $opts)
     {
         return $this->request('post', $this->basePath(), $params, $opts);
     }
 
+    protected function createNestedObject($nestedPath, $parentId, $params, $opts)
+    {
+        return $this->request('post', $this->baseNestedPath($parentId, $nestedPath), $params, $opts);
+    }
+
     protected function deleteObject($id, $params, $opts)
     {
         return $this->request('delete', $this->instancePath($id), $params, $opts);
     }
 
+    protected function deleteNestedObject($nestedPath, $parentId, $id, $params, $opts)
+    {
+        return $this->request('delete', $this->instanceNestedPath($parentId, $nestedPath, $id), $params, $opts);
+    }
+
     protected function retrieveObject($id, $params, $opts)
     {
         return $this->request('get', $this->instancePath($id), $params, $opts);
     }
 
+    protected function retrieveNestedObject($nestedPath, $parentId, $id, $params, $opts)
+    {
+        return $this->request('get', $this->instanceNestedPath($parentId, $nestedPath, $id), $params, $opts);
+    }
+
     protected function updateObject($id, $params, $opts)
     {
         return $this->request('post', $this->instancePath($id), $params, $opts);
     }
 
+    protected function updateNestedObject($nestedPath, $parentId, $id, $params, $opts)
+    {
+        return $this->request('post', $this->instanceNestedPath($parentId, $nestedPath, $id), $params, $opts);
+    }
+
     protected function request($method, $path, $params, $opts)
     {
         return $this->getClient()->request($method, $path, $params, $opts);
     }
 
+    protected function baseNestedPath($parentId, $nestedPath)
+    {
+        return $this->instancePath($parentId) . '/' . $nestedPath;
+    }
+
     protected function instancePath($id)
     {
         if (null === $id || '' === \trim($id)) {
@@ -80,4 +110,15 @@ protected function instancePath($id)
 
         return $this->basePath() . '/' . \urlencode($id);
     }
+
+    protected function instanceNestedPath($parentId, $nestedPath, $id)
+    {
+        if (null === $id || '' === \trim($id)) {
+            $msg = 'The resource ID cannot be null or whitespace.';
+
+            throw new \Stripe\Exception\InvalidArgumentException($msg);
+        }
+
+        return $this->baseNestedPath($parentId, $nestedPath) . '/' . \urlencode($id);
+    }
 }
diff --git a/lib/Service/CustomerService.php b/lib/Service/CustomerService.php
new file mode 100644
index 0000000000..0a9707afa8
--- /dev/null
+++ b/lib/Service/CustomerService.php
@@ -0,0 +1,306 @@
+<?php
+
+namespace Stripe\Service;
+
+class CustomerService extends AbstractService
+{
+    const BALANCE_TRANSACTIONS = 'balance_transactions';
+    const SOURCES = 'sources';
+    const TAX_IDS = 'tax_ids';
+
+    public function basePath()
+    {
+        return '/v1/customers';
+    }
+
+    /**
+     * List all customers.
+     *
+     * @param array $params
+     * @param array $opts
+     *
+     * @return \Stripe\Collection
+     */
+    public function all($params = [], $opts = [])
+    {
+        return $this->allObjects($params, $opts);
+    }
+
+    /**
+     * List customer balance transactions.
+     *
+     * @param string $customerId
+     * @param array $params
+     * @param array $opts
+     *
+     * @return \Stripe\Collection
+     */
+    public function allBalanceTransactions($customerId, $params = [], $opts = [])
+    {
+        return $this->allNestedObjects(self::BALANCE_TRANSACTIONS, $customerId, $params, $opts);
+    }
+
+    /**
+     * List all sources.
+     *
+     * @param string $customerId
+     * @param array $params
+     * @param array $opts
+     *
+     * @return \Stripe\Collection
+     */
+    public function allSources($customerId, $params = [], $opts = [])
+    {
+        return $this->allNestedObjects(self::SOURCES, $customerId, $params, $opts);
+    }
+
+    /**
+     * List all tax IDs.
+     *
+     * @param string $customerId
+     * @param array $params
+     * @param array $opts
+     *
+     * @return \Stripe\Collection
+     */
+    public function allTaxIds($customerId, $params = [], $opts = [])
+    {
+        return $this->allNestedObjects(self::TAX_IDS, $customerId, $params, $opts);
+    }
+
+    /**
+     * Create a customer.
+     *
+     * @param array $params
+     * @param array $opts
+     *
+     * @return \Stripe\Customer
+     */
+    public function create($params = [], $opts = [])
+    {
+        return $this->createObject($params, $opts);
+    }
+
+    /**
+     * Create a balance transaction.
+     *
+     * @param string $customerId
+     * @param array $params
+     * @param array $opts
+     *
+     * @return \Stripe\CustomerBalanceTransaction
+     */
+    public function createBalanceTransaction($customerId, $params = [], $opts = [])
+    {
+        return $this->createNestedObject(self::BALANCE_TRANSACTIONS, $customerId, $params, $opts);
+    }
+
+    /**
+     * Create a source.
+     *
+     * @param string $customerId
+     * @param array $params
+     * @param array $opts
+     *
+     * @return \Stripe\BankAccount|\Stripe\Card|\Stripe\Source
+     */
+    public function createSource($customerId, $params = [], $opts = [])
+    {
+        return $this->createNestedObject(self::SOURCES, $customerId, $params, $opts);
+    }
+
+    /**
+     * Create a tax ID.
+     *
+     * @param string $customerId
+     * @param array $params
+     * @param array $opts
+     *
+     * @return \Stripe\TaxId
+     */
+    public function createTaxId($customerId, $params = [], $opts = [])
+    {
+        return $this->createNestedObject(self::TAX_IDS, $customerId, $params, $opts);
+    }
+
+    /**
+     * Delete a customer.
+     *
+     * @param string $id
+     * @param array $params
+     * @param array $opts
+     *
+     * @return \Stripe\Customer
+     */
+    public function delete($id, $params = [], $opts = [])
+    {
+        return $this->deleteObject($id, $params, $opts);
+    }
+
+    /**
+     * Delete a customer discount.
+     *
+     * @param string $id
+     * @param array $params
+     * @param array $opts
+     *
+     * @return \Stripe\Discount
+     */
+    public function deleteDiscount($id, $params = [], $opts = [])
+    {
+        return $this->request('delete', $this->instancePath($id) . '/discount', $params, $opts);
+    }
+
+    /**
+     * Delete a source.
+     *
+     * @param string $customerId
+     * @param string $id
+     * @param array $params
+     * @param array $opts
+     *
+     * @return \Stripe\BankAccount|\Stripe\Card|\Stripe\Source
+     */
+    public function deleteSource($customerId, $id, $params = [], $opts = [])
+    {
+        return $this->deleteNestedObject(self::SOURCES, $customerId, $id, $params, $opts);
+    }
+
+    /**
+     * Delete a tax ID.
+     *
+     * @param string $customerId
+     * @param string $id
+     * @param array $params
+     * @param array $opts
+     *
+     * @return \Stripe\TaxId
+     */
+    public function deleteTaxId($customerId, $id, $params = [], $opts = [])
+    {
+        return $this->deleteNestedObject(self::TAX_IDS, $customerId, $id, $params, $opts);
+    }
+
+    /**
+     * Retrieve a customer.
+     *
+     * @param string $id
+     * @param array $params
+     * @param array $opts
+     *
+     * @return \Stripe\Customer
+     */
+    public function retrieve($id, $params = [], $opts = [])
+    {
+        return $this->retrieveObject($id, $params, $opts);
+    }
+
+    /**
+     * Retrieve a balance transaction.
+     *
+     * @param string $customerId
+     * @param string $id
+     * @param array $params
+     * @param array $opts
+     *
+     * @return \Stripe\CustomerBalanceTransaction
+     */
+    public function retrieveBalanceTransaction($customerId, $id, $params = [], $opts = [])
+    {
+        return $this->retrieveNestedObject(self::BALANCE_TRANSACTIONS, $customerId, $id, $params, $opts);
+    }
+
+    /**
+     * Retrieve a source.
+     *
+     * @param string $customerId
+     * @param string $id
+     * @param array $params
+     * @param array $opts
+     *
+     * @return \Stripe\BankAccount|\Stripe\Card|\Stripe\Source
+     */
+    public function retrieveSource($customerId, $id, $params = [], $opts = [])
+    {
+        return $this->retrieveNestedObject(self::SOURCES, $customerId, $id, $params, $opts);
+    }
+
+    /**
+     * Retrieve a tax ID.
+     *
+     * @param string $customerId
+     * @param string $id
+     * @param array $params
+     * @param array $opts
+     *
+     * @return \Stripe\TaxId
+     */
+    public function retrieveTaxId($customerId, $id, $params = [], $opts = [])
+    {
+        return $this->retrieveNestedObject(self::TAX_IDS, $customerId, $id, $params, $opts);
+    }
+
+    /**
+     * Update a customer.
+     *
+     * @param string $id
+     * @param array $params
+     * @param array $opts
+     *
+     * @return \Stripe\Customer
+     */
+    public function update($id, $params = [], $opts = [])
+    {
+        return $this->updateObject($id, $params, $opts);
+    }
+
+    /**
+     * Update a balance transaction.
+     *
+     * @param string $customerId
+     * @param string $id
+     * @param array $params
+     * @param array $opts
+     *
+     * @return \Stripe\CustomerBalanceTransaction
+     */
+    public function updateBalanceTransaction($customerId, $id, $params = [], $opts = [])
+    {
+        return $this->updateNestedObject(self::BALANCE_TRANSACTIONS, $customerId, $id, $params, $opts);
+    }
+
+    /**
+     * Update a source.
+     *
+     * @param string $customerId
+     * @param string $id
+     * @param array $params
+     * @param array $opts
+     *
+     * @return \Stripe\BankAccount|\Stripe\Card|\Stripe\Source
+     */
+    public function updateSource($customerId, $id, $params = [], $opts = [])
+    {
+        return $this->updateNestedObject(self::SOURCES, $customerId, $id, $params, $opts);
+    }
+
+    /**
+     * Verify a source.
+     *
+     * @param string $customerId
+     * @param string $id
+     * @param array $params
+     * @param array $opts
+     *
+     * @return \Stripe\BankAccount
+     */
+    public function verifySource($customerId, $id, $params = [], $opts = [])
+    {
+        return $this->request(
+            'post',
+            $this->instanceNestedPath($customerId, self::SOURCES, $id) . '/verify',
+            $params,
+            $opts
+        );
+    }
+}
diff --git a/tests/Stripe/Service/CustomerServiceTest.php b/tests/Stripe/Service/CustomerServiceTest.php
new file mode 100644
index 0000000000..79b2e68361
--- /dev/null
+++ b/tests/Stripe/Service/CustomerServiceTest.php
@@ -0,0 +1,243 @@
+<?php
+
+namespace Stripe\Service;
+
+/**
+ * @internal
+ */
+final class CustomerServiceTest extends \PHPUnit\Framework\TestCase
+{
+    use \Stripe\TestHelper;
+
+    const TEST_RESOURCE_ID = 'cus_123';
+    const TEST_CUSTOMER_BALANCE_TRANSACTION_ID = 'cbtxn_123';
+    const TEST_SOURCE_ID = 'card_123';
+    const TEST_TAX_ID_ID = 'txi_123';
+
+    private $client;
+    private $service;
+
+    /**
+     * @before
+     */
+    protected function setUpService()
+    {
+        $this->client = new \Stripe\StripeClient('sk_test_123', null, MOCK_URL);
+        $this->service = new CustomerService($this->client);
+    }
+
+    public function testAll()
+    {
+        $this->expectsRequest(
+            'get',
+            '/v1/customers'
+        );
+        $resources = $this->service->all();
+        static::assertInternalType('array', $resources->data);
+        static::assertInstanceOf(\Stripe\Customer::class, $resources->data[0]);
+    }
+
+    public function testAllBalanceTransactions()
+    {
+        $this->expectsRequest(
+            'get',
+            '/v1/customers/' . self::TEST_RESOURCE_ID . '/balance_transactions'
+        );
+        $resources = $this->service->allBalanceTransactions(self::TEST_RESOURCE_ID);
+        static::assertInternalType('array', $resources->data);
+        static::assertInstanceOf(\Stripe\CustomerBalanceTransaction::class, $resources->data[0]);
+    }
+
+    public function testAllSources()
+    {
+        $this->expectsRequest(
+            'get',
+            '/v1/customers/' . self::TEST_RESOURCE_ID . '/sources'
+        );
+        $resources = $this->service->allSources(self::TEST_RESOURCE_ID);
+        static::assertInternalType('array', $resources->data);
+    }
+
+    public function testAllTaxIds()
+    {
+        $this->expectsRequest(
+            'get',
+            '/v1/customers/' . self::TEST_RESOURCE_ID . '/tax_ids'
+        );
+        $resources = $this->service->allTaxIds(self::TEST_RESOURCE_ID);
+        static::assertInternalType('array', $resources->data);
+        static::assertInstanceOf(\Stripe\TaxId::class, $resources->data[0]);
+    }
+
+    public function testCreate()
+    {
+        $this->expectsRequest(
+            'post',
+            '/v1/customers'
+        );
+        $resource = $this->service->create();
+        static::assertInstanceOf(\Stripe\Customer::class, $resource);
+    }
+
+    public function testCreateBalanceTransaction()
+    {
+        $this->expectsRequest(
+            'post',
+            '/v1/customers/' . self::TEST_RESOURCE_ID . '/balance_transactions'
+        );
+        $resource = $this->service->createBalanceTransaction(self::TEST_RESOURCE_ID, [
+            'amount' => 1234,
+            'currency' => 'usd',
+        ]);
+        static::assertInstanceOf(\Stripe\CustomerBalanceTransaction::class, $resource);
+    }
+
+    public function testCreateSource()
+    {
+        $this->expectsRequest(
+            'post',
+            '/v1/customers/' . self::TEST_RESOURCE_ID . '/sources'
+        );
+        $resource = $this->service->createSource(self::TEST_RESOURCE_ID, ['source' => 'tok_123']);
+    }
+
+    public function testCreateTaxId()
+    {
+        $this->expectsRequest(
+            'post',
+            '/v1/customers/' . self::TEST_RESOURCE_ID . '/tax_ids'
+        );
+        $resource = $this->service->createTaxId(self::TEST_RESOURCE_ID, [
+            'type' => \Stripe\TaxId::TYPE_EU_VAT,
+            'value' => '11111',
+        ]);
+        static::assertInstanceOf(\Stripe\TaxId::class, $resource);
+    }
+
+    public function testDelete()
+    {
+        $this->expectsRequest(
+            'delete',
+            '/v1/customers/' . self::TEST_RESOURCE_ID
+        );
+        $resource = $this->service->delete(self::TEST_RESOURCE_ID);
+        static::assertInstanceOf(\Stripe\Customer::class, $resource);
+    }
+
+    public function testDeleteDiscount()
+    {
+        $this->expectsRequest(
+            'delete',
+            '/v1/customers/' . self::TEST_RESOURCE_ID . '/discount'
+        );
+        $resource = $this->service->deleteDiscount(self::TEST_RESOURCE_ID);
+        static::assertInstanceOf(\Stripe\Discount::class, $resource);
+    }
+
+    public function testDeleteSource()
+    {
+        $this->expectsRequest(
+            'delete',
+            '/v1/customers/' . self::TEST_RESOURCE_ID . '/sources/' . self::TEST_SOURCE_ID
+        );
+        $resource = $this->service->deleteSource(self::TEST_RESOURCE_ID, self::TEST_SOURCE_ID);
+    }
+
+    public function testDeleteTaxId()
+    {
+        $this->expectsRequest(
+            'delete',
+            '/v1/customers/' . self::TEST_RESOURCE_ID . '/tax_ids/' . self::TEST_TAX_ID_ID
+        );
+        $resource = $this->service->deleteTaxId(self::TEST_RESOURCE_ID, self::TEST_TAX_ID_ID);
+        static::assertInstanceOf(\Stripe\TaxId::class, $resource);
+    }
+
+    public function testRetrieve()
+    {
+        $this->expectsRequest(
+            'get',
+            '/v1/customers/' . self::TEST_RESOURCE_ID
+        );
+        $resource = $this->service->retrieve(self::TEST_RESOURCE_ID);
+        static::assertInstanceOf(\Stripe\Customer::class, $resource);
+    }
+
+    public function testRetrieveBalanceTransaction()
+    {
+        $this->expectsRequest(
+            'get',
+            '/v1/customers/' . self::TEST_RESOURCE_ID . '/balance_transactions/'
+                . self::TEST_CUSTOMER_BALANCE_TRANSACTION_ID
+        );
+        $resource = $this->service->retrieveBalanceTransaction(
+            self::TEST_RESOURCE_ID,
+            self::TEST_CUSTOMER_BALANCE_TRANSACTION_ID
+        );
+        static::assertInstanceOf(\Stripe\CustomerBalanceTransaction::class, $resource);
+    }
+
+    public function testRetrieveSource()
+    {
+        $this->expectsRequest(
+            'get',
+            '/v1/customers/' . self::TEST_RESOURCE_ID . '/sources/' . self::TEST_SOURCE_ID
+        );
+        $resource = $this->service->retrieveSource(self::TEST_RESOURCE_ID, self::TEST_SOURCE_ID);
+    }
+
+    public function testRetrieveTaxId()
+    {
+        $this->expectsRequest(
+            'get',
+            '/v1/customers/' . self::TEST_RESOURCE_ID . '/tax_ids/' . self::TEST_TAX_ID_ID
+        );
+        $resource = $this->service->retrieveTaxId(self::TEST_RESOURCE_ID, self::TEST_TAX_ID_ID);
+        static::assertInstanceOf(\Stripe\TaxId::class, $resource);
+    }
+
+    public function testUpdate()
+    {
+        $this->expectsRequest(
+            'post',
+            '/v1/customers/' . self::TEST_RESOURCE_ID
+        );
+        $resource = $this->service->update(self::TEST_RESOURCE_ID, [
+            'metadata' => ['key' => 'value'],
+        ]);
+        static::assertInstanceOf(\Stripe\Customer::class, $resource);
+    }
+
+    public function testUpdateBalanceTransaction()
+    {
+        $this->expectsRequest(
+            'post',
+            '/v1/customers/' . self::TEST_RESOURCE_ID . '/balance_transactions/'
+                . self::TEST_CUSTOMER_BALANCE_TRANSACTION_ID
+        );
+        $resource = $this->service->updateBalanceTransaction(
+            self::TEST_RESOURCE_ID,
+            self::TEST_CUSTOMER_BALANCE_TRANSACTION_ID,
+            ['description' => 'new']
+        );
+        static::assertInstanceOf(\Stripe\CustomerBalanceTransaction::class, $resource);
+    }
+
+    public function testUpdateSource()
+    {
+        $this->expectsRequest(
+            'post',
+            '/v1/customers/' . self::TEST_RESOURCE_ID . '/sources/' . self::TEST_SOURCE_ID
+        );
+        $resource = $this->service->updateSource(self::TEST_RESOURCE_ID, self::TEST_SOURCE_ID, ['name' => 'name']);
+    }
+
+    public function testVerifySource()
+    {
+        $this->expectsRequest(
+            'post',
+            '/v1/customers/' . self::TEST_RESOURCE_ID . '/sources/' . self::TEST_SOURCE_ID . '/verify'
+        );
+        $resource = $this->service->verifySource(self::TEST_RESOURCE_ID, self::TEST_SOURCE_ID, ['amounts' => [32, 45]]);
+    }
+}