diff --git a/VERSION.txt b/VERSION.txt
index e0178fd19665..c52673985d32 100644
--- a/VERSION.txt
+++ b/VERSION.txt
@@ -1 +1 @@
-5.10.22
\ No newline at end of file
+5.10.23
\ No newline at end of file
diff --git a/app/DataMapper/Tax/BaseRule.php b/app/DataMapper/Tax/BaseRule.php
index 4448c7525898..016a38840db9 100644
--- a/app/DataMapper/Tax/BaseRule.php
+++ b/app/DataMapper/Tax/BaseRule.php
@@ -130,9 +130,8 @@ class BaseRule implements RuleInterface
         return $this;
     }
 
-    public function shouldCalcTax(): bool
-    {
-        return $this->should_calc_tax;
+    public function shouldCalcTax(): bool {
+        return $this->should_calc_tax && $this->checkIfInvoiceLocked();
     }
     /**
      * Initializes the tax rule for the entity.
@@ -400,4 +399,36 @@ class BaseRule implements RuleInterface
         return ! in_array($iso_3166_2, array_merge($this->eu_country_codes, array_keys($this->region_codes)));
     }
 
+    private function checkIfInvoiceLocked(): bool
+    {
+        $lock_invoices = $this->client->getSetting('lock_invoices');
+
+        switch ($lock_invoices) {
+            case 'off':
+                return true;
+            case 'when_sent':
+                if ($this->invoice->status_id == Invoice::STATUS_SENT) {
+                    return false;
+                }
+
+                return true;
+
+            case 'when_paid':
+                if ($this->invoice->status_id == Invoice::STATUS_PAID) {
+                    return false;
+                }
+
+                return true;
+
+                //if now is greater than the end of month the invoice was dated - do not modify
+            case 'end_of_month':
+                if(\Carbon\Carbon::parse($this->invoice->date)->setTimezone($this->invoice->company->timezone()->name)->endOfMonth()->lte(now())) {
+                    return false;
+                }
+                return true;
+            default:
+                return true;
+        }
+    }
+
 }
diff --git a/config/ninja.php b/config/ninja.php
index b646985bb879..c6fc98216433 100644
--- a/config/ninja.php
+++ b/config/ninja.php
@@ -17,8 +17,8 @@ return [
     'require_https' => env('REQUIRE_HTTPS', true),
     'app_url' => rtrim(env('APP_URL', ''), '/'),
     'app_domain' => env('APP_DOMAIN', 'invoicing.co'),
-    'app_version' => env('APP_VERSION', '5.10.22'),
-    'app_tag' => env('APP_TAG', '5.10.22'),
+    'app_version' => env('APP_VERSION', '5.10.23'),
+    'app_tag' => env('APP_TAG', '5.10.23'),
     'minimum_client_version' => '5.0.16',
     'terms_version' => '1.0.1',
     'api_secret' => env('API_SECRET', false),