diff --git a/application/Billing/BillingController.php b/application/Billing/BillingController.php
index 4381c92fb..f32f8fecb 100644
--- a/application/Billing/BillingController.php
+++ b/application/Billing/BillingController.php
@@ -142,11 +142,11 @@ class BillingController extends mfBaseController {
     protected function importContractsAction() {
         $r = $this->request;
 
-        $last_run_ts = new mfConfig("voicecallhistory.contact-job.ts");
+        /*$last_run_ts = new mfConfig("voicecallhistory.contact-job.ts");
         if($last_run_ts->value() < date("U") - 86400) {
             $this->layout()->setFlash("Voicecall History Contract Job ist heute noch nicht gelaufen", "error");
             $this->redirect("Billing");
-        }
+        }*/
 
 
         $i = 0;
@@ -161,8 +161,8 @@ class BillingController extends mfBaseController {
 
         // for debugging to bill a specific month
         //$now_year = 2024;
-        //$now_month = 7;
-        //$now_day = 10;
+        //$now_month = 11;
+        //$now_day = 3;
 
         // XXX only for 1st Billing after IVT Import
         // Locking to July 2024 and keeping it for now
@@ -182,7 +182,8 @@ class BillingController extends mfBaseController {
 
         $contract_search = [
             "finish_date<" => mktime(2,0,0,$now_month, $now_day, $now_year),
-            "cancel_date_null_or_gte" => mktime(0,0,0,$now_month, 1, $now_year)
+            "cancel_date_null_or_gte" => mktime(0,0,0,$now_month, 1, $now_year),
+            //"owner_id" => 1221
         ];
 
         foreach(ContractModel::search($contract_search) as $contract) {
@@ -284,10 +285,12 @@ class BillingController extends mfBaseController {
                 $earliest_bill_date = clone $contract_finish_date;
                 $earliest_bill_date->modify("first day of this month");
                 $earliest_bill_date->setTime(0,0,0);
-
+                //var_dump($create_date, $earliest_bill_date, $finish_year, $finish_month);exit;
                 while($create_date->format("Y-m-d") >= $earliest_bill_date->format("Y-m-d")) {
                     if($last_create_date) {
+                        //var_dump($create_dates);
                         // just for safety / shouldn't happen
+                        break;
                         die("need-date ran out of dates");
                     }
 
@@ -295,6 +298,7 @@ class BillingController extends mfBaseController {
                         // this is the finish month, so set day back to day of finish_date, unless billing_period is more than 1 month
                         if($contract->billing_period == 1) {
                             $create_date->setDate($finish_year, $finish_month, $finish_day);
+                            //var_dump($create_date);
                         }
                         $last_create_date = true;
                     }
@@ -377,30 +381,32 @@ class BillingController extends mfBaseController {
                     $pc = $period_days / $total_days * 100;
                     $price = round($contract->price / 100 * $pc, 4);
 
-                    /*if($contract->id == 936) {
-                        echo "\n";
-                        echo "first day: ".$first_of_period->format("Y-m-d")."\n";
-                        echo "total_days: $total_days\n";
-                        echo "period_days: $period_days\n";
-                        echo "pc: $pc\n";
-                        echo "price: $price\n";
-                        exit;
-                    }*/
+                    /*
+                    if($contract->id == 12500) {
+                        echo "\n". "<br>";
+                        echo "first day: ".$first_of_period->format("Y-m-d")."\n". "<br>";
+                        echo "total_days: $total_days\n". "<br>";
+                        echo "period_days: $period_days\n". "<br>";
+                        echo "pc: $pc\n". "<br>";
+                        echo "contract price: ".$contract->price."\n". "<br>";
+                        echo "price: $price\n". "<br>";
+                        //exit;
 
-                    /*if($contract->id == 8766) {
+                        echo "\n". "<br>";
                         echo "start date: ".$start_date->format("Y-m-d H:i:s") . "<br>";
                         echo "end date: ".$end_date->format("Y-m-d H:i:s") . "<br><br>";
                         echo "first_of_period: " . $first_of_period->format("Y-m-d H:i:s") . "<br>";
                         echo "total days: $total_days<br>";
                         echo "period days: $period_days<br>";
                         echo "price: $price<br><br>";
-                        echo "classic days: $days<br>";
+                        //echo "classic days: $days<br>";
                         exit;
                     }*/
                 } else {
                     $price = $contract->price;
                 }
 
+                $this->createProductchangeCredit($contract, $start_date);
 
                 $owner = $contract->owner;
                 if ($contract->billingaddress_id) {
@@ -741,4 +747,199 @@ class BillingController extends mfBaseController {
         $this->redirect("Billing");
 
     }
+
+    private function createProductchangeCredit(Contract $contract, $start_date) {
+        $today = new DateTime("now");
+
+        // find previous contract if upgrade for crediting
+        $links = ContractLinkModel::search(["contract_id" => $contract->id, "type" => ["upgrade","downgrade","relocation","productchange"]]);
+        //var_dump($links);
+        if(!is_array($links) || count($links) !== 1) {
+            return false;
+        }
+
+        $link = array_shift($links);
+        //var_dump($link);
+        if($link->origin_contract_id == $contract->id) {
+            return false;
+        }
+
+        $origin_contract = $link->origin;
+        //var_dump($origin_contract);
+        if(!$origin_contract->cancel_date) {
+            return false;
+        }
+
+        $origin_cancel_date = new DateTime("@".$origin_contract->cancel_date);
+        $origin_cancel_date->setTimezone(new DateTimeZone("Europe/Vienna"));
+        //var_dump($link_cancel_date);
+        //var_dump($)
+        // link_cancel_date gleicher monat wie herstellungsdatum
+        // und
+        // link_cancel_date kleiner als herstellungsdatum
+
+        /*if($contract->id == 12527) {
+            echo "origin cancel date: ".$origin_cancel_date->format("m.Y")."\n<br/>";
+            echo "new cancel date: ".$start_date->format("m.Y")."\n<br/>";
+            exit;
+        }*/
+
+        if($origin_cancel_date->format("m") == $today->format("m") ||
+            ($origin_cancel_date->format("m.Y") != $start_date->format("m.Y") ||
+            $origin_cancel_date->format("d") > $start_date->format("d"))
+        ) {
+            return false;
+        }
+
+        $end_of_month = clone($start_date);
+        $end_of_month->modify("last day of this month");
+        $first_of_month = clone($start_date);
+        $first_of_month->modify("first day of this month");
+
+        $prev_bill = BillingModel::getFirst(["contract_id" => $origin_contract->id, "start_date>=" => $first_of_month->format("Y-m-d"), "end_date<=" => $end_of_month->format("Y-m-d")]);
+        //var_dump($prev_bill);
+        if(!$prev_bill) {
+            return false;
+        }
+
+        $prev_bill_end_date = new DateTime($prev_bill->end_date);
+        $prev_end_of_month = clone($prev_bill_end_date);
+        $prev_end_of_month->modify("Last day of this month");
+
+        $prev_cancel_date = new DateTime("@".$origin_contract->cancel_date);
+        $prev_cancel_date->modify("+1 days");
+        $prev_cancel_date->setTimezone(new DateTimeZone("Europe/Vienna"));
+        //var_dump($prev_cancel_date);
+        $credit_days = ($prev_end_of_month->diff($prev_cancel_date)->format("%a"))+2;
+        if($credit_days < 1) return false;
+
+        $credit_from_date = clone($end_of_month);
+        $credit_from_date->modify("-$credit_days days");
+
+        $credit_total_days = $prev_end_of_month->diff($first_of_month)->format("%a") + 1;
+        $credit_pc = $credit_days / $credit_total_days * 100;
+        $credit_price = round($origin_contract->price / 100 * $credit_pc, 4);
+        $credit_price *= -1;
+
+        /*
+        echo "prev end of month: ".$prev_end_of_month->format("Y-m-d H:i:s")."\n<br />";
+        echo "credit days: $credit_days\n<br />";
+        echo "credit pc: $credit_pc\n<br />";
+        exit;
+        */
+
+        /*
+        $period_days = ($end_date->diff($start_date)->format("%a")) + 1;
+        if ($period_days < 0) continue; // don't bill for negative time range
+        $pc = $period_days / $total_days * 100;
+        */
+
+        /*
+        echo $prev_cancel_date->format("d.m.Y") . " -> " . $prev_bill_end_date->format("d.m.Y") . "<br />\n";
+        echo "start date: " . $start_date->format("d.m.Y") . "<br />\n";
+        echo "credit days: " . $credit_days . "<br />\n";
+        exit;
+        */
+
+        // create credit bill
+        $credit_owner = $contract->owner;
+        if ($contract->billingaddress_id) {
+            $credit_billingaddress = $origin_contract->billingaddress;
+        } else {
+            $credit_billingaddress = $credit_owner;
+        }
+
+        $credit_billing_type = "invoice";
+        $credit_billing_delivery = "paper";
+
+        if ($credit_owner->billing_type) {
+            $credit_billing_type = $credit_owner->billing_type;
+        }
+        if ($credit_owner->billing_delivery) {
+            $credit_billing_delivery = $credit_owner->billing_delivery;
+        }
+
+        if ($credit_billingaddress->billing_type) {
+            $credit_billing_type = $credit_billingaddress->billing_type;
+        }
+        if ($credit_billingaddress->billing_delivery) {
+            $credit_billing_delivery = $credit_billingaddress->billing_delivery;
+        }
+
+        if($origin_contract->vatgroup_id == TT_VATGROUP_CREDIT) {
+            $credit_fibu_account_num = $credit_billingaddress->fibu_supplier_number;
+            if(!$credit_fibu_account_num) {
+                die("Partner " . $credit_billingaddress->customer_number . " hat keine Lieferantennummer (" . $credit_billingaddress->getCompanyOrName().")");
+            }
+        } else {
+            $credit_fibu_account_num = $credit_billingaddress->fibu_account_number;
+            if(!$credit_fibu_account_num) {
+                die("Keine Fibu Account Nummer in Rechnungskontakt in Contract ID ".$origin_contract->id);
+            }
+        }
+
+        $product_name = "Gutschrift zu ".$origin_contract->product_name;
+
+        $credit_data = [];
+        $credit_data["contract_id"] = $origin_contract->id;
+        $credit_data["start_date"] = $prev_cancel_date->format("Y-m-d");
+        $credit_data["end_date"] = $prev_bill_end_date->format("Y-m-d");
+        $credit_data["owner_id"] = $origin_contract->owner_id;
+        $credit_data["billingaddress_id"] = ($origin_contract->billingaddress_id) ? $origin_contract->billingaddress_id : $origin_contract->owner_id;
+        $credit_data["customer_number"] = $origin_contract->owner->customer_number;
+        $credit_data["fibu_account_number"] = $credit_fibu_account_num;
+        $credit_data["company"] = $credit_billingaddress->company;
+        $credit_data["firstname"] = $credit_billingaddress->firstname;
+        $credit_data["lastname"] = $credit_billingaddress->lastname;
+        $credit_data["street"] = $credit_billingaddress->street;
+        $credit_data["zip"] = $credit_billingaddress->zip;
+        $credit_data["city"] = $credit_billingaddress->city;
+        $credit_data["email"] = $credit_billingaddress->email;
+        $credit_data["uid"] = $credit_billingaddress->uid;
+        $credit_data["billing_type"] = $credit_billing_type;
+        $credit_data["billing_delivery"] = $credit_billing_delivery;
+        $credit_data["bank_account_bank"] = $credit_billingaddress->bank_account_bank;
+        $credit_data["bank_account_owner"] = $credit_billingaddress->bank_account_owner;
+        $credit_data["bank_account_iban"] = str_replace(" ", "", $credit_billingaddress->bank_account_iban);
+        $credit_data["bank_account_bic"] = $credit_billingaddress->bank_account_bic;
+        $credit_data["product_id"] = $origin_contract->product_id;
+        $credit_data["product_name"] = $product_name;
+        $credit_data["product_info"] = $origin_contract->product_info;
+        $credit_data["amount"] = $origin_contract->amount;
+        $credit_data["price"] = $credit_price;
+        $credit_data["price_setup"] = 0;
+        $credit_data["billing_period"] = $origin_contract->billing_period;
+        $credit_data["matchcode"] = $origin_contract->matchcode;
+
+        if(!$credit_billingaddress->country_id) {
+            $credit_billcountry = CountryModel::getFirst(["isocode" => TT_HOMECOUNTRY_ISOCODE]);
+        } else {
+            $credit_billcountry = $credit_billingaddress->country;
+        }
+
+        $credit_vatgroup = $origin_contract->vatgroup;
+        $credit_vatarea = "domestic";
+        if($credit_billcountry->isocode != TT_HOMECOUNTRY_ISOCODE && $credit_billcountry->is_eu) {
+            $credit_vatarea = "eu";
+        } if($credit_billcountry->isocode != TT_HOMECOUNTRY_ISOCODE && !$credit_billcountry->is_eu) {
+            $credit_vatarea = "other";
+        }
+
+        $credit_data["country"] = $credit_billcountry->name;
+        $credit_data["vatrate"] = $credit_vatgroup->rates[$credit_vatarea]->rate;
+        $credit_data["vatgroup_id"] = $origin_contract->vatgroup_id;
+        $credit_data["vatarea"] = $credit_vatarea;
+
+
+        //var_dump($credit_data);exit;
+        $credit = BillingModel::create($credit_data);
+        if(!$credit->save()) {
+            die("Error saving Billing record for Credit of Contract ".$origin_contract->id. " (Created from Upgrade to Contract ".$contract->id.")");
+        }
+
+        $this->log->info("Created Credit for Contract ".$origin_contract->id." (Created from Upgrade to Contract ".$contract->id.")");
+
+        return $credit;
+    }
+
 }
\ No newline at end of file