diff --git a/examples/KositValidator.php b/examples/KositValidator.php
index 0cac83a0..a50c801b 100644
--- a/examples/KositValidator.php
+++ b/examples/KositValidator.php
@@ -34,17 +34,24 @@ function showValidationResult(ZugferdKositValidator $kositValidator)
 }
 
 /* ----------------------------------------------------------------------------------
-   - Get instance of the Validator
+   - Validation of a document read by ZugferdDocumentPdfReader
+   - The direct call of the constructor is deprecated
    ---------------------------------------------------------------------------------- */
 
-$kositValidator = new ZugferdKositValidator();
+$document = ZugferdDocumentPdfReader::readAndGuessFromFile(dirname(__FILE__) . "/invoice_1.pdf");
+
+$kositValidator = new ZugferdKositValidator($document);
+$kositValidator->disableCleanup()->validate();
+
+showValidationResult($kositValidator);
 
 /* ----------------------------------------------------------------------------------
    - Validation of a document read by ZugferdDocumentPdfReader
    ---------------------------------------------------------------------------------- */
 
 $document = ZugferdDocumentPdfReader::readAndGuessFromFile(dirname(__FILE__) . "/invoice_1.pdf");
-$kositValidator->setDocument($document)->disableCleanup()->validate();
+
+$kositValidator = ZugferdKositValidator::fromDocument($document)->disableCleanup()->validate();
 
 showValidationResult($kositValidator);
 
@@ -54,7 +61,16 @@ function showValidationResult(ZugferdKositValidator $kositValidator)
 
 $document = ZugferdDocumentReader::readAndGuessFromFile(dirname(__FILE__) . "/../tests/assets/xml_en16931_5.xml");
 
-$kositValidator = new ZugferdKositValidator($document);
-$kositValidator->setDocument($document)->disableCleanup()->validate();
+$kositValidator = ZugferdKositValidator::fromDocument($document)->disableCleanup()->validate();
+
+showValidationResult($kositValidator);
+
+/* ----------------------------------------------------------------------------------
+   - Validation of a document read by content
+   ---------------------------------------------------------------------------------- */
+
+$content = file_get_contents(dirname(__FILE__) . "/../tests/assets/xml_en16931_4.xml");
+
+$kositValidator = ZugferdKositValidator::fromString($content)->disableCleanup()->validate();
 
 showValidationResult($kositValidator);
diff --git a/src/ZugferdDocumentBuilder.php b/src/ZugferdDocumentBuilder.php
index 202ae118..f14964c9 100644
--- a/src/ZugferdDocumentBuilder.php
+++ b/src/ZugferdDocumentBuilder.php
@@ -2761,13 +2761,13 @@ public function addNewPosition(string $lineid, ?string $lineStatusCode = null, ?
     /**
      * Adds a new text-only position (line) to document
      *
-     * @param  string      $lineid
+     * @param      string      $lineid
      * A unique identifier for the relevant item within the invoice (item number)
-     * @param  string|null $lineStatusCode
+     * @param      string|null $lineStatusCode
      * Indicates whether the invoice item contains prices that must be taken into account when
      * calculating the invoice amount, or whether it only contains information.
      * The following code should be used: TYPE_LINE
-     * @param  string|null $lineStatusReasonCode
+     * @param      string|null $lineStatusReasonCode
      * Adds the type to specify whether the invoice line is:
      *  - detail (normal position)
      *  - Subtotal
@@ -2776,7 +2776,7 @@ public function addNewPosition(string $lineid, ?string $lineStatusCode = null, ?
      *  - detail
      *  - grouping
      *  - information
-     * @return ZugferdDocumentBuilder
+     * @return     ZugferdDocumentBuilder
      * @deprecated 1.0.75
      */
     public function addNewTextPosition(string $lineid, ?string $lineStatusCode = null, ?string $lineStatusReasonCode = null): ZugferdDocumentBuilder
diff --git a/src/ZugferdKositValidator.php b/src/ZugferdKositValidator.php
index 8590480a..0e5ea62f 100644
--- a/src/ZugferdKositValidator.php
+++ b/src/ZugferdKositValidator.php
@@ -12,13 +12,14 @@
 use DOMDocument;
 use DOMXPath;
 use Exception;
+use Throwable;
+use ZipArchive;
 use horstoeko\stringmanagement\FileUtils;
 use horstoeko\stringmanagement\PathUtils;
 use horstoeko\stringmanagement\StringUtils;
+use JMS\Serializer\Exception\RuntimeException;
 use Symfony\Component\Process\ExecutableFinder;
 use Symfony\Component\Process\Process;
-use Throwable;
-use ZipArchive;
 
 /**
  * Class representing the validator against Schematron (Kosit) for documents
@@ -34,9 +35,9 @@ class ZugferdKositValidator
     /**
      * The invoice document reference
      *
-     * @var ZugferdDocument
+     * @var string
      */
-    private $document = null;
+    private $documentContent = null;
 
     /**
      * Internal message bag
@@ -134,25 +135,71 @@ class ZugferdKositValidator
     protected const MSG_TYPE_PROCESSOUTPUT = 'processoutput';
 
     /**
-     * Constructor
+     * Constructo
      *
-     * @param ZugferdDocument|null $document
+     * @deprecated 1.0.76 Use static::fromDocument or static::fromString instead
      */
     public function __construct(?ZugferdDocument $document = null)
     {
-        $this->document = $document;
         $this->baseDirectory = sys_get_temp_dir();
+
+        if (!is_null($document)) {
+            $this->setDocumentContent($document->serializeAsXml());
+        }
     }
 
     /**
-     * Set the ZugferdDocument instance to validate
+     * Initialize from a ZugferdDocument to validate
      *
      * @param  ZugferdDocument $document
-     * @return ZugferdKositValidator
+     * @return static
+     */
+    public static function fromDocument(ZugferdDocument $document)
+    {
+        $instance = new static();
+        $instance->setDocumentContent($document->serializeAsXml());
+
+        return $instance;
+    }
+
+    /**
+     * Initialize from a string which contains the XML to validate
+     *
+     * @param  string $documentContent
+     * @return static
+     */
+    public static function fromString(string $documentContent)
+    {
+        $instance = new static();
+        $instance->setDocumentContent($documentContent);
+
+        return $instance;
+    }
+
+    /**
+     * Set the ZugferdDocument instance to validate
+     *
+     * @param      ZugferdDocument $document
+     * @return     ZugferdKositValidator
+     * @throws     RuntimeException
+     * @deprecated 1.0.76 Use static::fromDocument or static::fromString instead
      */
     public function setDocument(ZugferdDocument $document): ZugferdKositValidator
     {
-        $this->document = $document;
+        $this->setDocumentContent($document->serializeAsXml());
+
+        return $this;
+    }
+
+    /**
+     * Sets the content to validate
+     *
+     * @param  string $documentContent
+     * @return ZugferdKositValidator
+     */
+    public function setDocumentContent(string $documentContent): ZugferdKositValidator
+    {
+        $this->documentContent = $documentContent;
 
         return $this;
     }
@@ -577,8 +624,8 @@ public function getProcessOutput(): array
      */
     private function checkRequirements(): bool
     {
-        if (is_null($this->document)) {
-            $this->addToMessageBag("You must specify an instance of the ZugferdDocument class");
+        if (empty($this->documentContent)) {
+            $this->addToMessageBag("You must specify the content to validate");
             return false;
         }
 
@@ -683,7 +730,7 @@ private function unpackRequiredFile(string $filename): bool
      */
     private function performValidation(): bool
     {
-        if (file_put_contents($this->resolveFileToValidateFilename(), $this->document->serializeAsXml()) === false) {
+        if (file_put_contents($this->resolveFileToValidateFilename(), $this->documentContent) === false) {
             $this->addToMessageBag("Cannot create temporary file which contains the XML to validate");
             return false;
         }
diff --git a/src/ZugferdXsdValidator.php b/src/ZugferdXsdValidator.php
index 37ce1a8e..fd61c381 100644
--- a/src/ZugferdXsdValidator.php
+++ b/src/ZugferdXsdValidator.php
@@ -9,15 +9,14 @@
 
 namespace horstoeko\zugferd;
 
-use Exception;
 use DOMDocument;
+use Exception;
 use LibXMLError;
+use Throwable;
 use horstoeko\stringmanagement\PathUtils;
 use horstoeko\zugferd\exception\ZugferdFileNotFoundException;
 use horstoeko\zugferd\ZugferdDocument;
 use horstoeko\zugferd\ZugferdSettings;
-use PhpParser\Node\Expr\Throw_;
-use Throwable;
 
 /**
  * Class representing the validator against XSD for documents