diff --git a/resources/assets/js/views/common/documents.js b/resources/assets/js/views/common/documents.js
index f94c05ba1..bf0f3452c 100644
--- a/resources/assets/js/views/common/documents.js
+++ b/resources/assets/js/views/common/documents.js
@@ -811,15 +811,20 @@ const app = new Vue({
 
     watch: {
         'form.discount': function (newVal, oldVal) {
-            if (newVal != '' && newVal.search('^(?=.*?[0-9])[0-9.,]+$') !== 0) {
+            if (newVal > 99) {
+                newVal = oldVal;
+                return;
+            }
+            
+            if (newVal != '' && newVal.search('^[-+]?([0-9]|[1-9][0-9]|100)*\.?[0-9]+$') !== 0) {
                 this.form.discount = oldVal;
-                this.form.discount = this.form.discount.replace(',', '.');
+                this.form.discount = this.form.discount ? this.form.discount.replace(',', '.') : '';
 
                 return;
             }
 
             for (let item of this.regex_condition) {
-                if (this.form.discount.includes(item)) {
+                if (this.form.discount && this.form.discount.includes(item)) {
                     const removeLastChar  = newVal.length - 1;
                     const inputShown = newVal.slice(0, removeLastChar);
 
@@ -827,7 +832,7 @@ const app = new Vue({
                 }
             }
 
-            this.form.discount = this.form.discount.replace(',', '.');
+            this.form.discount = this.form.discount ? this.form.discount.replace(',', '.') : '';
         },
 
         'form.loading': function (newVal, oldVal) {