diff --git a/app/Services/TaxInvoiceService.php b/app/Services/TaxInvoiceService.php
index 19cd6c8..58718ac 100644
--- a/app/Services/TaxInvoiceService.php
+++ b/app/Services/TaxInvoiceService.php
@@ -112,6 +112,12 @@ public function create(array $data): TaxInvoice
         // 합계금액 계산
         $data['total_amount'] = ($data['supply_amount'] ?? 0) + ($data['tax_amount'] ?? 0);
 
+        // NOT NULL 컬럼: Laravel ConvertEmptyStringsToNull 미들웨어가 ''→null 변환하므로 보정
+        $data['supplier_corp_num'] = $data['supplier_corp_num'] ?? '';
+        $data['supplier_corp_name'] = $data['supplier_corp_name'] ?? '';
+        $data['buyer_corp_num'] = $data['buyer_corp_num'] ?? '';
+        $data['buyer_corp_name'] = $data['buyer_corp_name'] ?? '';
+
         $taxInvoice = TaxInvoice::create(array_merge($data, [
             'tenant_id' => $tenantId,
             'status' => TaxInvoice::STATUS_DRAFT,