diff --git a/app/apps/rules/forms.py b/app/apps/rules/forms.py
index f86134d..25a8c35 100644
--- a/app/apps/rules/forms.py
+++ b/app/apps/rules/forms.py
@@ -3,6 +3,7 @@ from crispy_forms.bootstrap import FormActions
 from crispy_forms.helper import FormHelper
 from crispy_forms.layout import Layout, Field, Row, Column
 from django import forms
+from django.core.exceptions import ValidationError
 from django.utils.translation import gettext_lazy as _
 
 from apps.rules.models import TransactionRule
@@ -66,6 +67,8 @@ class TransactionRuleActionForm(forms.ModelForm):
         widgets = {"field": TomSelect(clear_button=False)}
 
     def __init__(self, *args, **kwargs):
+        self.rule = kwargs.pop("rule", None)
+
         super().__init__(*args, **kwargs)
 
         self.helper = FormHelper()
@@ -93,3 +96,22 @@ class TransactionRuleActionForm(forms.ModelForm):
                     ),
                 ),
             )
+
+    def clean(self):
+        cleaned_data = super().clean()
+        field = cleaned_data.get("field")
+
+        if field and self.rule:
+            if TransactionRuleAction.objects.filter(
+                rule=self.rule, field=field
+            ).exists():
+                raise ValidationError(
+                    _("A value for this field already exists in the rule.")
+                )
+
+    def save(self, commit=True):
+        instance = super().save(commit=False)
+        instance.rule = self.rule
+        if commit:
+            instance.save()
+        return instance
diff --git a/app/apps/rules/models.py b/app/apps/rules/models.py
index 80f2fe0..39596f9 100644
--- a/app/apps/rules/models.py
+++ b/app/apps/rules/models.py
@@ -42,3 +42,6 @@ class TransactionRuleAction(models.Model):
 
     def __str__(self):
         return f"{self.rule} - {self.field} - {self.value}"
+
+    class Meta:
+        unique_together = (("rule", "field"),)
diff --git a/app/apps/rules/views.py b/app/apps/rules/views.py
index 9e1ea9c..87beb6b 100644
--- a/app/apps/rules/views.py
+++ b/app/apps/rules/views.py
@@ -142,11 +142,9 @@ def transaction_rule_action_add(request, transaction_rule_id):
     transaction_rule = get_object_or_404(TransactionRule, id=transaction_rule_id)
 
     if request.method == "POST":
-        form = TransactionRuleActionForm(request.POST)
+        form = TransactionRuleActionForm(request.POST, rule=transaction_rule)
         if form.is_valid():
-            action = form.save(commit=False)
-            action.rule = transaction_rule
-            action.save()
+            form.save()
 
             return HttpResponse(
                 status=204,
@@ -155,7 +153,7 @@ def transaction_rule_action_add(request, transaction_rule_id):
                 },
             )
     else:
-        form = TransactionRuleActionForm()
+        form = TransactionRuleActionForm(rule=transaction_rule)
 
     return render(
         request,