diff --git a/app/Casts/InvoiceBackupCast.php b/app/Casts/InvoiceBackupCast.php
new file mode 100644
index 0000000000..817ff2b489
--- /dev/null
+++ b/app/Casts/InvoiceBackupCast.php
@@ -0,0 +1,60 @@
+<?php
+
+/**
+ * Invoice Ninja (https://invoiceninja.com).
+ *
+ * @link https://github.com/invoiceninja/invoiceninja source repository
+ *
+ * @copyright Copyright (c) 2025. Invoice Ninja LLC (https://invoiceninja.com)
+ *
+ * @license https://www/elastic.co/licensing/elastic-license
+ */
+
+namespace App\Casts;
+
+use App\DataMapper\InvoiceBackup;
+use Illuminate\Contracts\Database\Eloquent\CastsAttributes;
+
+class InvoiceBackupCast implements CastsAttributes
+{
+    public function get($model, string $key, $value, array $attributes)
+    {
+        if (is_null($value)) {
+            return new InvoiceBackup();
+        }
+
+        $data = json_decode($value, true) ?? [];
+
+        return InvoiceBackup::fromArray($data);
+    }
+
+    public function set($model, string $key, $value, array $attributes)
+    {
+        if (is_null($value)) {
+            return [$key => null];
+        }
+
+        // Ensure we're dealing with our object type
+        if (! $value instanceof InvoiceBackup) {
+            throw new \InvalidArgumentException('Value must be an InvoiceBackup instance.');
+        }
+
+        return [
+            $key => json_encode([
+                'guid' => $value->guid,
+                'cancellation' => $value->cancellation ? [
+                    'adjustment' => $value->cancellation->adjustment,
+                    'status_id' => $value->cancellation->status_id,
+                ] : [],
+                'cancelled_invoice_id' => $value->cancelled_invoice_id,
+                'cancelled_invoice_number' => $value->cancelled_invoice_number,
+                'cancellation_reason' => $value->cancellation_reason,
+                'credit_invoice_id' => $value->credit_invoice_id,
+                'credit_invoice_number' => $value->credit_invoice_number,
+                'redirect' => $value->redirect,
+                'modified_invoice_id' => $value->modified_invoice_id,
+                'replaced_invoice_id' => $value->replaced_invoice_id,
+            ])
+        ];
+    }
+}
diff --git a/app/DataMapper/Cancellation.php b/app/DataMapper/Cancellation.php
new file mode 100644
index 0000000000..5d4fab7f8e
--- /dev/null
+++ b/app/DataMapper/Cancellation.php
@@ -0,0 +1,32 @@
+<?php
+
+/**
+ * Invoice Ninja (https://invoiceninja.com).
+ *
+ * @link https://github.com/invoiceninja/invoiceninja source repository
+ *
+ * @copyright Copyright (c) 2025. Invoice Ninja LLC (https://invoiceninja.com)
+ *
+ * @license https://www/elastic.co/licensing/elastic-license
+ */
+
+namespace App\DataMapper;
+
+/**
+ * Cancellation value object for invoice backup data.
+ */
+class Cancellation
+{
+    public function __construct(
+        public float $adjustment = 0, // The cancellation adjustment amount
+        public int $status_id = 0 //The status id of the invoice when it was cancelled
+    ) {}
+
+    public static function fromArray(array $data): self
+    {
+        return new self(
+            adjustment: $data['adjustment'] ?? 0,
+            status_id: $data['status_id'] ?? 0
+        );
+    }
+}
diff --git a/app/DataMapper/InvoiceBackup.php b/app/DataMapper/InvoiceBackup.php
new file mode 100644
index 0000000000..9370013aa9
--- /dev/null
+++ b/app/DataMapper/InvoiceBackup.php
@@ -0,0 +1,63 @@
+<?php
+
+/**
+ * Invoice Ninja (https://invoiceninja.com).
+ *
+ * @link https://github.com/invoiceninja/invoiceninja source repository
+ *
+ * @copyright Copyright (c) 2025. Invoice Ninja LLC (https://invoiceninja.com)
+ *
+ * @license https://www/elastic.co/licensing/elastic-license
+ */
+
+namespace App\DataMapper;
+
+use App\Casts\InvoiceBackupCast;
+use App\DataMapper\Cancellation;
+use Illuminate\Contracts\Database\Eloquent\Castable;
+
+/**
+ * InvoiceBackup.
+ */
+class InvoiceBackup implements Castable
+{
+    public function __construct(
+        public string $guid = '', // The E-INVOICE SENT GUID reference 
+        public Cancellation $cancellation = new Cancellation(0,0), 
+        public ?string $cancelled_invoice_id = null, // The id of the invoice that was cancelled
+        public ?string $cancelled_invoice_number = null, // The number of the invoice that was cancelled
+        public ?string $cancellation_reason = null, // The reason for the cancellation
+        public ?string $credit_invoice_id = null, // The id of the credit invoice that was created
+        public ?string $credit_invoice_number = null, // The number of the credit invoice that was created
+        public ?string $redirect = null, // The redirect url for the invoice
+        public ?string $modified_invoice_id = null, // The id of the modified invoice (replaces the invoice with replaced_invoice_id)
+        public ?string $replaced_invoice_id = null // The id of the replaced invoice (The previous invoice that was replaced by the modified invoice)
+    ) {}
+
+    /**
+     * Get the name of the caster class to use when casting from / to this cast target.
+     *
+     * @param  array<string, mixed>  $arguments
+     */
+    public static function castUsing(array $arguments): string
+    {
+        return InvoiceBackupCast::class;
+    }
+
+    public static function fromArray(array $data): self
+    {
+        return new self(
+            guid: $data['guid'] ?? '',
+            cancellation: Cancellation::fromArray($data['cancellation'] ?? []),
+            cancelled_invoice_id: $data['cancelled_invoice_id'] ?? null,
+            cancelled_invoice_number: $data['cancelled_invoice_number'] ?? null,
+            cancellation_reason: $data['cancellation_reason'] ?? null,
+            credit_invoice_id: $data['credit_invoice_id'] ?? null,
+            credit_invoice_number: $data['credit_invoice_number'] ?? null,
+            redirect: $data['redirect'] ?? null,
+            modified_invoice_id: $data['modified_invoice_id'] ?? null,
+            replaced_invoice_id: $data['replaced_invoice_id'] ?? null
+        );
+    }
+}
+
diff --git a/app/Http/ValidationRules/Invoice/CanGenerateModificationInvoice.php b/app/Http/ValidationRules/Invoice/CanGenerateModificationInvoice.php
index 7b3cd22fd3..7c76655576 100644
--- a/app/Http/ValidationRules/Invoice/CanGenerateModificationInvoice.php
+++ b/app/Http/ValidationRules/Invoice/CanGenerateModificationInvoice.php
@@ -57,6 +57,8 @@ class CanGenerateModificationInvoice implements ValidationRule
             $fail("Cannot create a modification invoice for a reversed invoice.");
         } elseif ($invoice->status_id !== Invoice::STATUS_SENT) {
             $fail("Cannot create a modification invoice.");
+        } elseif($invoice->amount <= 0){
+            $fail("Cannot create a modification invoice for an invoice with an amount less than 0.");
         }
 
     }
diff --git a/app/Models/Invoice.php b/app/Models/Invoice.php
index a83e15a471..4efcc8ca92 100644
--- a/app/Models/Invoice.php
+++ b/app/Models/Invoice.php
@@ -29,6 +29,7 @@ use App\Helpers\Invoice\InvoiceSumInclusive;
 use App\Utils\Traits\Invoice\ActionsInvoice;
 use Illuminate\Database\Eloquent\SoftDeletes;
 use App\Events\Invoice\InvoiceReminderWasEmailed;
+use App\DataMapper\InvoiceBackup;
 use App\Utils\Number;
 
 /**
@@ -55,7 +56,7 @@ use App\Utils\Number;
  * @property string|null $due_date
  * @property bool $is_deleted
  * @property object|array|string $line_items
- * @property object|null $backup
+ * @property InvoiceBackup $backup
  * @property object|null $sync
  * @property string|null $footer
  * @property string|null $public_notes
@@ -207,7 +208,7 @@ class Invoice extends BaseModel
 
     protected $casts = [
         'line_items' => 'object',
-        'backup' => 'object',
+        'backup' => InvoiceBackup::class,
         'updated_at' => 'timestamp',
         'created_at' => 'timestamp',
         'deleted_at' => 'timestamp',
diff --git a/app/Repositories/BaseRepository.php b/app/Repositories/BaseRepository.php
index 3b17647eeb..e7c253d61b 100644
--- a/app/Repositories/BaseRepository.php
+++ b/app/Repositories/BaseRepository.php
@@ -328,6 +328,11 @@ class BaseRepository
                     nlog($e->getMessage());
                 }
             }
+
+            /** Verifactu modified invoice check */
+            if(isset($data['verifactu_modified']) && $data['verifactu_modified']) {
+                $model->service()->modifyVerifactuWorkflow($data['modified_invoice_id'])->save();
+            }
         }
 
         if ($model instanceof Credit) {
diff --git a/app/Services/EDocument/Jobs/SendEDocument.php b/app/Services/EDocument/Jobs/SendEDocument.php
index 794e660bbe..383667154b 100644
--- a/app/Services/EDocument/Jobs/SendEDocument.php
+++ b/app/Services/EDocument/Jobs/SendEDocument.php
@@ -59,7 +59,7 @@ class SendEDocument implements ShouldQueue
 
         $model = $this->entity::withTrashed()->find($this->id);
 
-        if(isset($model->backup->guid) && is_string($model->backup->guid)){
+        if(isset($model->backup->guid) && is_string($model->backup->guid) && strlen($model->backup->guid) > 3){
             nlog("already sent!");
             return;
         }
@@ -217,9 +217,9 @@ class SendEDocument implements ShouldQueue
 
         if($activity_id == Activity::EINVOICE_DELIVERY_SUCCESS){
 
-            $backup = ($model->backup && is_object($model->backup)) ? $model->backup : new \stdClass();
-            $backup->guid = str_replace('"', '', $notes);
-            $model->backup = $backup;
+            // $backup = ($model->backup && is_object($model->backup)) ? $model->backup : new \stdClass();
+            // $backup->guid = str_replace('"', '', $notes);
+            $model->backup->guid = str_replace('"', '', $notes);
             $model->saveQuietly();
 
         }
diff --git a/app/Services/Invoice/HandleCancellation.php b/app/Services/Invoice/HandleCancellation.php
index 480f80cfef..a84f08f372 100644
--- a/app/Services/Invoice/HandleCancellation.php
+++ b/app/Services/Invoice/HandleCancellation.php
@@ -87,10 +87,11 @@ class HandleCancellation extends AbstractService
 
         $replicated_invoice->line_items = $items;
 
-        $backup = new \stdClass();
-        $backup->cancelled_invoice_id = $this->invoice->hashed_id;
-        $backup->cancelled_invoice_number = $this->invoice->number;
-        $backup->cancellation_reason = $this->reason ?? 'R3';
+        $backup = new \App\DataMapper\InvoiceBackup(
+            cancelled_invoice_id: $this->invoice->hashed_id,
+            cancelled_invoice_number: $this->invoice->number,
+            cancellation_reason: $this->reason ?? 'R3'
+        );
 
         $replicated_invoice->backup = $backup;
 
@@ -98,10 +99,11 @@ class HandleCancellation extends AbstractService
         $replicated_invoice = $invoice_repository->save([], $replicated_invoice);
         $replicated_invoice->service()->markSent()->sendVerifactu()->save();
 
-        $old_backup = new \stdClass();
-        $old_backup->credit_invoice_id = $replicated_invoice->hashed_id;
-        $old_backup->credit_invoice_number = $replicated_invoice->number;
-        $old_backup->cancellation_reason = $this->reason ?? 'R3';
+        $old_backup = new \App\DataMapper\InvoiceBackup(
+            credit_invoice_id: $replicated_invoice->hashed_id,
+            credit_invoice_number: $replicated_invoice->number,
+            cancellation_reason: $this->reason ?? 'R3'
+        );
 
         $this->invoice->backup = $old_backup;
         $this->invoice->saveQuietly();
@@ -115,10 +117,9 @@ class HandleCancellation extends AbstractService
 
     public function reverse()
     {
-        /* The stored cancelled object - contains the adjustment and status*/
-        $cancellation = $this->invoice->backup->cancellation;
-
         /* Will turn the negative cancellation amount to a positive adjustment*/
+        
+        $cancellation = $this->invoice->backup->cancellation;
         $adjustment = $cancellation->adjustment * -1;
 
         $this->invoice->ledger()->updateInvoiceBalance($adjustment, "Invoice {$this->invoice->number} reversal");
@@ -133,11 +134,9 @@ class HandleCancellation extends AbstractService
 
         $this->invoice->client->service()->calculateBalance();
 
-
-        /* Pop the cancellation out of the backup*/
-        $backup = $this->invoice->backup;
-        unset($backup->cancellation);
-        $this->invoice->backup = $backup;
+        /* Clear the cancellation data */
+        $this->invoice->backup->cancellation->adjustment = 0;
+        $this->invoice->backup->cancellation->status_id = 0;
         $this->invoice->saveQuietly();
         $this->invoice->fresh();
 
@@ -152,19 +151,11 @@ class HandleCancellation extends AbstractService
      */
     private function backupCancellation($adjustment)
     {
-        if (! is_object($this->invoice->backup)) {
-            $backup = new stdClass();
-            $this->invoice->backup = $backup;
-        }
 
-        $cancellation = new stdClass();
-        $cancellation->adjustment = $adjustment;
-        $cancellation->status_id = $this->invoice->status_id;
-
-        $invoice_backup = $this->invoice->backup;
-        $invoice_backup->cancellation = $cancellation;
-
-        $this->invoice->backup = $invoice_backup;
+        // Direct assignment to properties
+        $this->invoice->backup->cancellation->adjustment = $adjustment;
+        $this->invoice->backup->cancellation->status_id = $this->invoice->status_id;
+        
         $this->invoice->saveQuietly();
     }
 }
diff --git a/app/Services/Invoice/InvoiceService.php b/app/Services/Invoice/InvoiceService.php
index 2d56cd823c..5eff5093a4 100644
--- a/app/Services/Invoice/InvoiceService.php
+++ b/app/Services/Invoice/InvoiceService.php
@@ -708,6 +708,33 @@ class InvoiceService
 
         return $this;
     }
+    
+    /**
+     * modifyVerifactuWorkflow
+     * @todo - handle invoice modifications - ensure when we 
+     * sent this to AEAT we reference the invoice that was replaced.
+     * 
+     * @param  string $modified_invoice_hashed_id
+     * @return self
+     */
+    public function modifyVerifactuWorkflow(string $modified_invoice_hashed_id): self
+    {
+        $modified_invoice = Invoice::withTrashed()->find($this->decodePrimaryKey($modified_invoice_hashed_id));
+        $modified_invoice->status_id = Invoice::STATUS_REPLACED;
+        $modified_invoice->backup->modified_invoice_id = $this->invoice->hashed_id;
+        $modified_invoice->save();
+
+        $this->markSent();
+        //Update the client balance by the delta amount from the previous invoice to this one.
+        $this->invoice->backup->replaced_invoice_id = $modified_invoice->hashed_id;
+        $this->invoice->saveQuietly();
+
+        $this->invoice->client->service()->updateBalance(round(($modified_invoice->amount - $this->invoice->amount), 2));
+        $this->sendVerifactu();
+        
+        return $this;
+    }
+
     /**
      * Saves the invoice.
      * @return Invoice object
diff --git a/app/Services/Invoice/TriggeredActions.php b/app/Services/Invoice/TriggeredActions.php
index 0721a6db03..54eda85dff 100644
--- a/app/Services/Invoice/TriggeredActions.php
+++ b/app/Services/Invoice/TriggeredActions.php
@@ -81,7 +81,7 @@ class TriggeredActions extends AbstractService
             $company->save();
         }
 
-        if($this->request->has('retry_e_send') && $this->request->input('retry_e_send') == 'true' && !isset($this->invoice->backup->guid) && $this->invoice->client->peppolSendingEnabled()) {    
+        if($this->request->has('retry_e_send') && $this->request->input('retry_e_send') == 'true' && strlen($this->invoice->backup->guid ?? '') < 2 && $this->invoice->client->peppolSendingEnabled()) {    
             \App\Services\EDocument\Jobs\SendEDocument::dispatch(get_class($this->invoice), $this->invoice->id, $this->invoice->company->db);
         }
 
@@ -90,9 +90,9 @@ class TriggeredActions extends AbstractService
             $redirectUrl = urldecode($this->request->input('redirect'));
 
             if (filter_var($redirectUrl, FILTER_VALIDATE_URL)) {
-                $backup = ($this->invoice->backup && is_object($this->invoice->backup)) ? $this->invoice->backup : new \stdClass();
-                $backup->redirect = $redirectUrl;
-                $this->invoice->backup = $backup;
+                // $backup = ($this->invoice->backup && is_object($this->invoice->backup)) ? $this->invoice->backup : new \stdClass();
+                // $backup->redirect = $redirectUrl;
+                $this->invoice->backup->redirect = $redirectUrl;
                 $this->invoice->saveQuietly();
             }
             
diff --git a/app/Transformers/InvoiceTransformer.php b/app/Transformers/InvoiceTransformer.php
index 87c56c1f7c..253ebab520 100644
--- a/app/Transformers/InvoiceTransformer.php
+++ b/app/Transformers/InvoiceTransformer.php
@@ -171,7 +171,7 @@ class InvoiceTransformer extends EntityTransformer
             'auto_bill_enabled' => (bool) $invoice->auto_bill_enabled,
             'tax_info' => $invoice->tax_data ?: new \stdClass(),
             'e_invoice' => $invoice->e_invoice ?: new \stdClass(),
-            'backup' => $invoice->backup ?: new \stdClass(),
+            'backup' => $invoice->backup,
             'location_id' => $this->encodePrimaryKey($invoice->location_id),
         ];