Validate tax rates to be between 0 and 100

src/pretix/base/models/tax.py

@@ -23,6 +23,7 @@ import json
 from decimal import Decimal
 
 from django.core.exceptions import ValidationError
+from django.core.validators import MaxValueValidator, MinValueValidator
 from django.db import models
 from django.utils.formats import localize
 from django.utils.translation import gettext_lazy as _, pgettext
@@ -149,7 +150,15 @@ class TaxRule(LoggedModel):
     rate = models.DecimalField(
         max_digits=10,
         decimal_places=2,
-        verbose_name=_("Tax rate")
+        validators=[
+            MaxValueValidator(
+                limit_value=Decimal("100.00"),
+            ),
+            MinValueValidator(
+                limit_value=Decimal("0.00"),
+            ),
+        ],
+        verbose_name=_("Tax rate"),
     )
     price_includes_tax = models.BooleanField(
         verbose_name=_("The configured product prices include the tax amount"),

src/pretix/control/forms/event.py

@@ -34,6 +34,7 @@
 # distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 # License for the specific language governing permissions and limitations under the License.
 
+from decimal import Decimal
 from urllib.parse import urlencode, urlparse
 
 from django import forms
@@ -135,6 +136,8 @@ class EventWizardBasicsForm(I18nModelForm):
         help_text=_("Do you need to pay sales tax on your tickets? In this case, please enter the applicable tax rate "
                     "here in percent. If you have a more complicated tax situation, you can add more tax rates and "
                     "detailed configuration later."),
+        max_value=Decimal("100.00"),
+        min_value=Decimal("0.00"),
         required=False
     )