diff --git a/client/src/app/quotes/components/editors/QuoteDetailsCardEditor.tsx b/client/src/app/quotes/components/editors/QuoteDetailsCardEditor.tsx
index 91e84e6..db8ac82 100644
--- a/client/src/app/quotes/components/editors/QuoteDetailsCardEditor.tsx
+++ b/client/src/app/quotes/components/editors/QuoteDetailsCardEditor.tsx
@@ -225,6 +225,7 @@ export const QuoteDetailsCardEditor = ({
   const handleAppendBlock = useCallback(
     (block: any) => {
       fieldActions.append({
+        id_article: "",
         description: `${block.title}\n${block.body}`,
         quantity: {
           amount: null,
diff --git a/server/src/contexts/catalog/domain/entities/ArticleIdentifier.test.ts b/server/src/contexts/catalog/domain/entities/ArticleIdentifier.test.ts
index 83d8a27..d4ba0e3 100644
--- a/server/src/contexts/catalog/domain/entities/ArticleIdentifier.test.ts
+++ b/server/src/contexts/catalog/domain/entities/ArticleIdentifier.test.ts
@@ -6,6 +6,15 @@ describe("ArticleIdentifier", () => {
     expect(ArticleIdentifier.create(Number.MAX_SAFE_INTEGER).isSuccess).toBe(true);
   });
 
+  it("normalizes missing identifiers to null for free quote lines", () => {
+    for (const value of ["", undefined]) {
+      const result = ArticleIdentifier.create(value);
+
+      expect(result.isSuccess).toBe(true);
+      expect(result.object?.isNull()).toBe(true);
+    }
+  });
+
   it("rejects zero, decimals, non-numeric, negative and unsafe identifiers", () => {
     expect(ArticleIdentifier.create(0).isFailure).toBe(true);
     expect(ArticleIdentifier.create(1.5).isFailure).toBe(true);
diff --git a/server/src/contexts/catalog/domain/entities/ArticleIdentifier.ts b/server/src/contexts/catalog/domain/entities/ArticleIdentifier.ts
index 83c8504..c28cd80 100644
--- a/server/src/contexts/catalog/domain/entities/ArticleIdentifier.ts
+++ b/server/src/contexts/catalog/domain/entities/ArticleIdentifier.ts
@@ -16,7 +16,7 @@ export class ArticleIdentifier extends NullableValueObject<number> {
   ) {
     const ruleNull = RuleValidator.RULE_ALLOW_NULL_OR_UNDEFINED.default(null);
 
-    const ruleEmpty = RuleValidator.RULE_ALLOW_EMPTY.default(null);
+    const ruleEmpty = RuleValidator.RULE_ALLOW_EMPTY.empty("").default(null);
 
     const ruleNumber = RuleValidator.RULE_IS_TYPE_NUMBER.label(
       options.label ? options.label : "ArticleIdentifier"
@@ -35,7 +35,7 @@ export class ArticleIdentifier extends NullableValueObject<number> {
     return value ? Number(value) : null;
   }
 
-  public static create(value: NullOr<number | string>, options: IArticleIdentifierOptions = {}) {
+  public static create(value: NullOr<number | string> = null, options: IArticleIdentifierOptions = {}) {
     const _options = {
       label: "ArticleIdentifier",
       ...options,
@@ -52,7 +52,7 @@ export class ArticleIdentifier extends NullableValueObject<number> {
     if (typeof validationResult.object === "string") {
       _value = parseInt(validationResult.object, 10);
     } else {
-      _value = validationResult.object;
+      _value = validationResult.object ?? null;
     }
 
     if (_value !== null && (!Number.isSafeInteger(_value) || _value <= 0)) {