diff --git a/composer.json b/composer.json
index f24d119..ae34fb8 100644
--- a/composer.json
+++ b/composer.json
@@ -13,8 +13,9 @@
         "psr-4": {"InvoiceNinja\\Sdk\\": "src/"}
     },
     "require": {
-        "php": "^7.4|^8.0|^8.1",
-        "guzzlehttp/guzzle": "^7.3"
+        "php": "^8.1|^8.2",
+        "guzzlehttp/guzzle": "^7.5",
+        "nesbot/carbon": "^2.66"
     },
     "require-dev": {
         "fakerphp/faker": "^1.16",
diff --git a/src/Exceptions/ApiException.php b/src/Exceptions/ApiException.php
index 0da12db..6ca5f27 100644
--- a/src/Exceptions/ApiException.php
+++ b/src/Exceptions/ApiException.php
@@ -32,6 +32,7 @@ protected static function parseResponseBody($response)
         $body = (string) $response->getBody();
         $error = "";
         $object = @json_decode($body);
+        $error_array = [];
 
         if(property_exists($object, "message"))
             $error = $object->message;
@@ -40,10 +41,10 @@ protected static function parseResponseBody($response)
         {
             $properties = array_keys(get_object_vars($object->errors));
 
-            if(is_array($properties))
+            if(is_array($properties) && count($properties) >=1)
                 $error_array = $object->errors->{$properties[0]};
 
-            if(is_array($error_array))
+            if(is_array($error_array) && count($error_array) >=1)
                 $error = $error_array[0];
 
         }
diff --git a/src/Exceptions/ModelValidationException.php b/src/Exceptions/ModelValidationException.php
new file mode 100644
index 0000000..081f61b
--- /dev/null
+++ b/src/Exceptions/ModelValidationException.php
@@ -0,0 +1,16 @@
+<?php
+/**
+ * Invoice Ninja (https://invoiceninja.com).
+ *
+ * @link https://github.com/invoiceninja/sdk-php source repository
+ *
+ * @copyright Copyright (c) 2022. Invoice Ninja LLC (https://invoiceninja.com)
+ *
+ * @license https://opensource.org/licenses/MIT
+ */
+
+namespace InvoiceNinja\Sdk\Exceptions;
+
+class ModelValidationException extends \Exception
+{
+}
\ No newline at end of file
diff --git a/src/Models/BaseModel.php b/src/Models/BaseModel.php
new file mode 100644
index 0000000..48deed3
--- /dev/null
+++ b/src/Models/BaseModel.php
@@ -0,0 +1,87 @@
+<?php
+/**
+ * Invoice Ninja (https://invoiceninja.com).
+ *
+ * @link https://github.com/invoiceninja/sdk-php source repository
+ *
+ * @copyright Copyright (c) 2022. Invoice Ninja LLC (https://invoiceninja.com)
+ *
+ * @license https://opensource.org/licenses/MIT
+ */
+
+namespace InvoiceNinja\Sdk\Models;
+
+use InvoiceNinja\Sdk\Exceptions\ModelValidationException;
+
+class BaseModel
+{
+	private array $validation_errors = [];
+
+    public function validate(): bool | ModelValidationException
+    {
+        $this->resetValidationErrors();
+
+        foreach($this->rules as $key => $rule)
+        {
+
+            switch($rule)
+            {
+                case 'required':
+                    isset($this->{$key}) ?: $this->setValidationErrors(["error" => "{$this->model} - `{$key}` must be set", "code" => 422]);
+                    break;
+                case 'date':
+                    isset($this->{$key}) ? $this->checkDate($key) : true;
+                    break;
+                default:
+                	$this->setValidationErrors(["error" => "{$this->model} - Unknown validation rule `{$rule}` for property `{$key}`", "code" => 500]);
+
+            }
+
+        }
+
+        if(count($this->getValidationErrors()) == 0)
+        	return true;
+
+        throw new ModelValidationException($this->getValidationErrors()[0]["error"] ,$this->getValidationErrors()[0]["code"]);
+    }
+
+    private function resetValidationErrors()
+    {
+        $this->validation_errors = [];
+
+        return $this;
+    }
+
+    private function setValidationErrors($error): self
+    {
+        $this->validation_errors[] = $error;
+
+        return $this;
+    }
+
+    public function getValidationErrors(): array
+    {
+        return $this->validation_errors;
+    }
+
+    public function checkDate(string $date_field): bool
+    {
+
+        try {
+
+            $parsed_date = \Carbon\Carbon::parse($this->{$date_field});
+            $this->{$date_field} = $parsed_date->format('Y-m-d');
+
+            return true;
+        }
+        catch(\Exception $e) {
+            $this->setValidationErrors([$date_field => "Invalid date format for field {$date_field} - '{$this->{$date_field}}'"]);
+            return false;
+        }
+    }
+
+
+
+
+
+}
\ No newline at end of file
diff --git a/src/Models/Client.php b/src/Models/Client.php
new file mode 100644
index 0000000..d53d70a
--- /dev/null
+++ b/src/Models/Client.php
@@ -0,0 +1,279 @@
+<?php
+/**
+ * Invoice Ninja (https://invoiceninja.com).
+ *
+ * @link https://github.com/invoiceninja/sdk-php source repository
+ *
+ * @copyright Copyright (c) 2022. Invoice Ninja LLC (https://invoiceninja.com)
+ *
+ * @license https://opensource.org/licenses/MIT
+ */
+
+namespace InvoiceNinja\Sdk\Models;
+
+use InvoiceNinja\Sdk\Models\ClientContact;
+use InvoiceNinja\Sdk\Models\ClientSettings;
+
+class Client extends BaseModel
+{
+    protected string $model = 'Client';
+
+    /**
+     *  The client name - required
+     */
+    public ?string $name = null;
+
+    /**
+     * The website ie https://example.com - optional
+     */
+    public ?string $website = null;
+
+    /**
+     * Private Notes - optional
+     */
+    public ?string $private_notes = null;
+    /**
+     * Public Notes - optional
+     */
+    public ?string $public_notes = null;
+
+    /**
+     * Phone - optional
+     */
+    public ?string $phone = null;
+
+    /**
+     * VAT/GST/Tax number - optional
+     */
+    public ?string $vat_number = null;
+
+    /**
+     * ID number - optional
+     */
+    public ?string $id_number = null;
+
+    /**
+     * Number - optional
+     */
+    public ?string $number = null;
+
+    /**
+     * Custom value 1 - optional
+     */
+    public ?string $custom_value1 = null;
+
+    /**
+     * Custom value 2 - optional
+     */
+    public ?string $custom_value2 = null;
+
+    /**
+     * Custom value 3 - optional
+     */
+    public ?string $custom_value3 = null;
+    
+    /**
+     * Custom value 4 - optional
+     */    
+    public ?string $custom_value4 = null;
+
+    /**
+     * The array of client contacts. This is optional, however
+     * the API will always set a blank ClientContact if none are set
+     * 
+     * @var ClientContact[]
+     */
+    public array $contacts = [];
+
+    /**
+     * Industry ID - optional
+     */
+    public ?int $industry_id = null;
+
+    /**
+     * Size ID - optional
+     */
+    public ?int $size_id = null;
+
+    /**
+     * Address line 1 - optional
+     */
+    public ?string $address1 = null;
+
+    /**
+     * Address line 2 - optional
+     */
+    public ?string $address2 = null;
+    
+    /**
+     * City - optional
+     */
+    public ?string $city = null;
+    
+    /**
+     * State - optional
+     */
+    public ?string $state = null;
+    
+    /**
+     * Postal Code - optional
+     */
+    public ?string $postal_code = null;
+
+    /**
+     * Country ID - optional|autoset If no value is set
+     * then the system will apply the company country ID.
+     * For the full list of country IDs you can use this reference
+     * 
+     * https://invoiceninja.github.io/docs/statics/#page-content
+     */
+    public ?string $country_id = null;
+
+    /**
+     * Country Code - optional iso_3166_2 or iso_3166_3 country code
+     * This can be used optionally instead of the country_id field
+     */
+    public ?string $country_code = null;
+
+    /**
+     * Shipping Address line 1 - optional
+     */
+    public ?string $shipping_address1 = null;
+
+    /**
+     * Shipping Address line 2 - optional
+     */
+    public ?string $shipping_address2 = null;
+    
+    /**
+     * Shipping City - optional
+     */
+    public ?string $shipping_city = null;
+    
+    /**
+     * Shipping State - optional
+     */
+    public ?string $shipping_state = null;
+    
+    /**
+     * Shipping Postal Code - optional
+     */
+    public ?string $shipping_postal_code = null;
+
+    /**
+     * Shipping Country ID - optional
+     *      
+     * https://invoiceninja.github.io/docs/statics/#page-content
+     */
+    public ?string $shipping_country_id = null;
+
+    /**
+     * @property-read float $balance - The client Balance
+     */
+
+    public float $balance;
+
+    /**
+     * @property-read float $credit_balance - The client credit_balance
+     */
+
+    public float $credit_balance;
+
+    /**
+     * @property-read float $paid_to_date - The client paid_to_date
+     */
+
+    public float $paid_to_date;
+
+    /**
+     * @var ClientSettings $settings
+     *
+     * The client settings object
+     */
+
+    public ClientSettings $client_settings;
+    
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+    protected array $rules = [
+        'name' => 'required',
+    ];
+
+    public function __construct()
+    {
+
+    }
+
+    public function setContact(ClientContact $contact): self
+    {
+        $this->contacts = array_merge($this->contacts, $contact);
+
+        return $this;
+    }
+
+    public function getContacts(): array
+    {
+        return $this->contacts;
+    }
+
+    public function save()
+    {
+        $this->validate();
+    }
+}
diff --git a/src/Models/ClientContact.php b/src/Models/ClientContact.php
new file mode 100644
index 0000000..35d46a0
--- /dev/null
+++ b/src/Models/ClientContact.php
@@ -0,0 +1,59 @@
+<?php
+/**
+ * Invoice Ninja (https://invoiceninja.com).
+ *
+ * @link https://github.com/invoiceninja/sdk-php source repository
+ *
+ * @copyright Copyright (c) 2022. Invoice Ninja LLC (https://invoiceninja.com)
+ *
+ * @license https://opensource.org/licenses/MIT
+ */
+
+namespace InvoiceNinja\Sdk\Models;
+
+class ClientContact extends BaseModel
+{
+    protected string $model = 'ClientContact';
+
+    /**
+     * The first name of the contact - optional
+     * 
+     */
+    public string $first_name = '';
+    
+    /**
+     * The last name of the contact - optional
+     * 
+     */
+    public string $last_name = '';
+    
+    /**
+     * Email - optional
+     * 
+     */
+    public string $email = '';
+
+    /**
+     * Phone number - optional
+     * 
+     */
+    public string $phone = '';
+
+    /**
+     * Flag for whether the contact will 
+     * receive emails. - optional 
+     *
+     * default - true
+     * 
+     */
+    public bool $send_email = true;
+
+    public string $custom_value1 = '';
+
+    public string $custom_value2 = '';
+
+    public string $custom_value3 = '';
+
+    public string $custom_value4 = '';
+
+}
\ No newline at end of file
diff --git a/src/Models/ClientSettings.php b/src/Models/ClientSettings.php
new file mode 100644
index 0000000..cdc936e
--- /dev/null
+++ b/src/Models/ClientSettings.php
@@ -0,0 +1,71 @@
+<?php
+/**
+ * Invoice Ninja (https://invoiceninja.com).
+ *
+ * @link https://github.com/invoiceninja/sdk-php source repository
+ *
+ * @copyright Copyright (c) 2022. Invoice Ninja LLC (https://invoiceninja.com)
+ *
+ * @license https://opensource.org/licenses/MIT
+ */
+
+namespace InvoiceNinja\Sdk\Models;
+
+class ClientSettings extends BaseModel
+{
+
+    /**
+     * The language ID for the client, for the full
+     * list of languages, please see this resource - optional
+     *
+     * @link https://invoiceninja.github.io/docs/statics/#languages
+     * 
+     */
+    public ?string $language_id = null;
+
+    /**
+     * The currency id - REQUIRED
+     * 
+     * @link https://invoiceninja.github.io/docs/statics/#currencies
+     */
+    public ?string $currency_id = null;
+
+    /**
+     * The payment terms - in days - optional
+     *
+     * example '10'
+     *
+     * Due in 10 days
+     * 
+     */
+    public ?string $payment_terms = null;
+
+    /**
+     * The quote terms, - optional
+     *
+     * How many days the quote will be valid for
+     *
+     * example '10'
+     *
+     * Quote will expire in 10 days
+     * 
+     */
+    public ?string $valid_until = null;
+
+    /**
+     * The task rate for this client. - optional
+     *
+     * A value of 0 equates to disabled. 
+     * 
+     */
+    public float $default_task_rate = 0;
+
+    /**
+     * Whether the client will receive reminders - optional
+     *
+     * When left unset, this setting will rely on the company
+     * settings as the override/default
+     */
+    public bool $send_reminders; 
+
+}
\ No newline at end of file
diff --git a/src/Models/Invoice.php b/src/Models/Invoice.php
new file mode 100644
index 0000000..3627330
--- /dev/null
+++ b/src/Models/Invoice.php
@@ -0,0 +1,265 @@
+<?php
+/**
+ * Invoice Ninja (https://invoiceninja.com).
+ *
+ * @link https://github.com/invoiceninja/sdk-php source repository
+ *
+ * @copyright Copyright (c) 2022. Invoice Ninja LLC (https://invoiceninja.com)
+ *
+ * @license https://opensource.org/licenses/MIT
+ */
+
+namespace InvoiceNinja\Sdk\Models;
+
+use InvoiceNinja\Sdk\Models\Client;
+
+class Invoice extends BaseModel
+{
+
+    protected string $model = 'Invoice';
+
+    public const STATUS_DRAFT = 1;
+
+
+    /**
+     *  The status of the invoice - readonly
+     *
+     *  STATUS_DRAFT = 1;
+     *  STATUS_SENT = 2;
+     *  STATUS_PARETIAL = 3;
+     *  STATUS_PAID = 4;
+     */
+    public int $status_id = self::STATUS_DRAFT;
+
+    /**
+     * Invoice number - optional
+     *
+     * The system will apply this if no invoice number is set.
+     * The invoice number _must_ be unique else a validation
+     * error will be returned
+     */
+    public ?string $number = null;
+
+    /**
+     * Discount - optional
+     * 
+     */
+    public float $discount = 0;
+
+    /**
+     * Is amount discount - optional
+     *
+     * If set true, a discount is set in a currency amount
+     * If set false a discount is set in a percentage
+     */
+    public bool $is_amount_discount = true;
+
+    /**
+     * Purchase order - optional
+     * 
+     */
+    public string $po_number = '';
+
+    /**
+     * Invoice footer - optional
+     *
+     * If a default company footer is set, then it will
+     * be applied if nothing is set
+     */
+    public string $footer = '';
+
+
+    /**
+     * Invoice terms - optional
+     *
+     * If a default company terms is set, then it will
+     * be applied if nothing is set
+     */
+    public string $terms = '';
+
+    /**
+     * Public notes - optional
+     * 
+     */
+    public string $public_notes = '';
+
+    /**
+     * Private notes - optional
+     * 
+     */
+    public string $private_notes = '';
+
+    /**
+     * The invoice date - optional
+     *
+     * format Y-m-d
+     *
+     * If left blank the API will set todays date
+     */
+    public ?string $date = null;
+
+
+    /**
+     * The invoice due date - optional
+     *
+     * format Y-m-d
+     *
+     * If left blank the API will set the due date
+     * based on the default payment terms - if set
+     */
+    public ?string $due_date = null;
+
+    /**
+     * Partial / Deposit - optional
+     * 
+     */
+    public float $partial = 0;
+
+    /**
+     * The invoice partial due date - optional
+     *
+     * format Y-m-d
+     *
+     * The date which the partial / deposit is due
+     */
+    public ?string $partial_due_date = null;
+
+    /**
+     * A boolean flag which defines if the invoice 
+     * is deleted
+     * 
+     * @property-read bool $is_deleted
+     */
+    public bool $is_deleted = false;
+
+    /**
+     * A array of invoice items - optional
+     * 
+     * @var InvoiceItem[]
+     */
+    public array $line_items = [];
+
+    /**
+     * Tax Name 1 name - optional
+     *
+     * ie GST
+     */
+    public string $tax_name1 = '';
+
+    /**
+     * Tax Rate 1 - optional
+     *
+     * ie 10
+     */
+    public float $tax_rate1 = 0;
+
+    /**
+     * Tax Name 2 name - optional
+     *
+     * ie GST
+     */
+    public string $tax_name2 = '';
+
+    /**
+     * Tax Rate 2 - optional
+     *
+     * ie 10
+     */
+    public float $tax_rate2 = 0;
+
+
+    /**
+     * Tax Name 3 name - optional
+     *
+     * ie GST
+     */
+    public string $tax_name3 = '';
+
+    /**
+     * Tax Rate 3 - optional
+     *
+     * ie 10
+     */
+    public float $tax_rate3 = 0;
+
+    /**
+     * Custom value - optional
+     * 
+     */
+    public ?string $custom_value1 = null;
+
+    /**
+     * Custom value - optional
+     * 
+     */
+    public ?string $custom_value2 = null;
+
+    /**
+     * Custom value - optional
+     * 
+     */
+    public ?string $custom_value3 = null;
+
+    /**
+     * Custom value - optional
+     * 
+     */
+    public ?string $custom_value4 = null;
+
+    /**
+     * Exchange rate - optional
+     *
+     * default 1
+     */
+    public float $exchange_rate = 1;
+
+    /**
+     * Client ID - required
+     *
+     * The hashed ID of the client
+     * 
+     */
+    public ?string $client_id = null;
+
+    protected array $rules = [
+        'client_id' => 'required',
+        'date' => 'date',
+        'due_date' => 'date',
+        'partial_due_date' => 'date',
+    ];
+
+    private array $validation_errors = [];
+
+    public function __construct()
+    {
+
+    }
+
+    public function setClient(Client $client): self
+    {
+        $this->client_id = $client->id;
+
+        return $this;
+    }
+
+    public function setClientId(string $client_id): self
+    {
+        $this->client_id = $client->id;
+
+        return $this;
+    }
+
+    public function addLine(InvoiceItem $item)
+    {
+        $this->line_items = array_merge($this->line_items, $item);
+
+        return $this;
+    }
+
+
+    //////////////////////////////////////// helpers - for abstraction///////////////////////////////////////////
+
+
+
+
+}
\ No newline at end of file
diff --git a/src/Models/InvoiceItem.php b/src/Models/InvoiceItem.php
new file mode 100644
index 0000000..a7b4f47
--- /dev/null
+++ b/src/Models/InvoiceItem.php
@@ -0,0 +1,83 @@
+<?php
+/**
+ * Invoice Ninja (https://invoiceninja.com).
+ *
+ * @link https://github.com/invoiceninja/sdk-php source repository
+ *
+ * @copyright Copyright (c) 2022. Invoice Ninja LLC (https://invoiceninja.com)
+ *
+ * @license https://opensource.org/licenses/MIT
+ */
+
+namespace InvoiceNinja\Sdk\Models;
+
+class InvoiceItem extends BaseModel
+{
+    protected string $model = 'InvoiceItem';
+
+    public const TYPE_PRODUCT = '1';
+
+    public const TYPE_SERVICE = '2';
+
+    public const TYPE_UNPAID_GATEWAY_FEE = '3';
+    
+    public const TYPE_PAID_GATEWAY_FEE = '4';
+
+    public const TYPE_LATE_FEE = '5';
+
+    public const TYPE_EXPENSE = '6';
+
+    public float $quantity = 0;
+
+    public float $cost = 0;
+
+    public string $product_key = '';
+
+    public float $product_cost = 0;
+
+    public string $notes = '';
+
+    public float $discount = 0;
+
+    public bool $is_amount_discount = false;
+
+    public string $tax_name1 = '';
+
+    public float $tax_rate1 = 0;
+
+    public string $tax_name2 = '';
+
+    public float $tax_rate2 = 0;
+
+    public string $tax_name3 = '';
+
+    public float $tax_rate3 = 0;
+
+    public string $sort_id = '0';
+
+    public float $line_total = 0;
+
+    public float $gross_line_total = 0;
+    
+    public float $tax_amount = 0;
+
+    public string $date = '';
+
+    public string $custom_value1 = '';
+
+    public string $custom_value2 = '';
+
+    public string $custom_value3 = '';
+
+    public string $custom_value4 = '';
+
+    /**
+     * See the consts in this file for
+     * the range of values 
+     *
+     * By default the product type will
+     * be used.
+     */
+    public $type_id = self::TYPE_PRODUCT;
+
+}
diff --git a/tests/BankIntegrationsTest.php b/tests/BankIntegrationsTest.php
index ac55c44..bbdf47c 100644
--- a/tests/BankIntegrationsTest.php
+++ b/tests/BankIntegrationsTest.php
@@ -33,7 +33,7 @@ public function testBankIntegrations()
         $ninja->setUrl($this->url);
 
         $bank_integrations = $ninja->bank_integrations->create(['bank_account_name' => $this->faker->firstName]);
-        
+
         $this->assertTrue(is_array($bank_integrations));
         
     } 
diff --git a/tests/Invoice/CreateInvoiceTest.php b/tests/Invoice/CreateInvoiceTest.php
new file mode 100644
index 0000000..220acb0
--- /dev/null
+++ b/tests/Invoice/CreateInvoiceTest.php
@@ -0,0 +1,72 @@
+<?php
+/**
+ * Invoice Ninja (https://invoiceninja.com).
+ *
+ * @link https://github.com/invoiceninja/sdk-php source repository
+ *
+ * @copyright Copyright (c) 2022. Invoice Ninja LLC (https://invoiceninja.com)
+ *
+ * @license https://opensource.org/licenses/MIT
+ */
+
+namespace InvoiceNinja\Sdk\Tests\Invoice;
+
+use InvoiceNinja\Sdk\InvoiceNinja;
+use InvoiceNinja\Sdk\Models\Client;
+use InvoiceNinja\Sdk\Models\Invoice;
+use InvoiceNinja\Sdk\Models\InvoiceItem;
+use PHPUnit\Framework\TestCase;
+
+class CreateInvoiceTest extends TestCase
+{
+    protected string $token = "company-token-test";
+    protected string $url = "http://ninja.test:8000";
+
+    public function setUp() :void
+    {
+        parent::setUp();
+        $this->faker = \Faker\Factory::create();
+    }
+
+    // $ninja = new InvoiceNinja($this->token);
+    // $ninja->setUrl($this->url);
+
+    public function testInitInvoice()
+    {
+        $invoice = new Invoice();
+        $this->assertInstanceOf(Invoice::class, $invoice);
+    } 
+
+    public function testInitItem()
+    {
+        $item = new InvoiceItem();
+        $this->assertInstanceOf(InvoiceItem::class, $item);
+    } 
+
+    public function testBaseName()
+    {
+        $client = new Client;
+
+        $this->assertEquals("InvoiceNinja\Sdk\Models\Client", get_class($client));
+    }
+
+    public function testClientValidation()
+    {
+         $client = new Client;
+         $client->name = 'Jim';
+         
+         $client->save();    
+
+         $this->assertInstanceOf(Client::class, $client);    
+    }
+
+    // public function testBuildInvoice()
+    // {
+    //     $client = new Client;
+    //     $client->name = 'Jim';
+    //     $client->save();
+
+    //     $invoice = new Invoice;
+    //     $invoice->setClient($client);
+    // }
+}
\ No newline at end of file