diff --git a/app/DataMapper/CompanySettings.php b/app/DataMapper/CompanySettings.php
index 049f807d5743..d9ffe3792038 100644
--- a/app/DataMapper/CompanySettings.php
+++ b/app/DataMapper/CompanySettings.php
@@ -139,6 +139,8 @@ class CompanySettings extends BaseSettings
     public $payment_type_id = '0'; //@TODO where do we use this?
     // public $invoice_fields = ''; //@TODO is this redundant, we store this in the custom_fields on the company?
 
+    public $valid_until = ''; //@implemented
+
     public $show_accept_invoice_terms = false; //@TODO ben to confirm
     public $show_accept_quote_terms = false;  //@TODO ben to confirm
     public $require_invoice_signature = false;  //@TODO ben to confirm
@@ -430,6 +432,7 @@ class CompanySettings extends BaseSettings
         'show_accept_quote_terms'            => 'bool',
         'show_accept_invoice_terms'          => 'bool',
         'timezone_id'                        => 'string',
+        'valid_until'                        => 'string',
         'date_format_id'                     => 'string',
         'military_time'                      => 'bool',
         'language_id'                        => 'string',
diff --git a/app/Services/Quote/MarkSent.php b/app/Services/Quote/MarkSent.php
index aebe2d4b35a2..d91617324708 100644
--- a/app/Services/Quote/MarkSent.php
+++ b/app/Services/Quote/MarkSent.php
@@ -14,6 +14,7 @@ namespace App\Services\Quote;
 use App\Events\Quote\QuoteWasMarkedSent;
 use App\Models\Quote;
 use App\Utils\Ninja;
+use Carbon\Carbon;
 
 class MarkSent
 {
@@ -37,6 +38,13 @@ class MarkSent
 
         $this->quote->markInvitationsSent();
 
+        if ($this->quote->due_date != '' || $this->quote->client->getSetting('valid_until') == '') {
+            
+        }
+        else{
+            $this->quote->due_date = Carbon::parse($this->quote->date)->addDays($this->quote->client->getSetting('valid_until'));
+        }
+
         event(new QuoteWasMarkedSent($this->quote, $this->quote->company, Ninja::eventVars()));
 
         $this->quote