diff --git a/nummi/main/admin.py b/nummi/main/admin.py
index ea0111a..d8bde1e 100644
--- a/nummi/main/admin.py
+++ b/nummi/main/admin.py
@@ -1,6 +1,7 @@
 from django.contrib import admin
 
-from .models import Transaction, Invoice
+from .models import Transaction, Invoice, Category
 
 admin.site.register(Transaction)
 admin.site.register(Invoice)
+admin.site.register(Category)
diff --git a/nummi/main/migrations/0002_category_transaction_category.py b/nummi/main/migrations/0002_category_transaction_category.py
new file mode 100644
index 0000000..be19f25
--- /dev/null
+++ b/nummi/main/migrations/0002_category_transaction_category.py
@@ -0,0 +1,28 @@
+# Generated by Django 4.0.4 on 2022-05-20 11:34
+
+from django.db import migrations, models
+import django.db.models.deletion
+import uuid
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('main', '0001_initial'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='Category',
+            fields=[
+                ('id', models.UUIDField(default=uuid.uuid4, editable=False, primary_key=True, serialize=False)),
+                ('name', models.CharField(max_length=256)),
+                ('parent', models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.SET_NULL, to='main.category')),
+            ],
+        ),
+        migrations.AddField(
+            model_name='transaction',
+            name='category',
+            field=models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.SET_NULL, to='main.category'),
+        ),
+    ]
diff --git a/nummi/main/models.py b/nummi/main/models.py
index a5f30f4..8e6a895 100644
--- a/nummi/main/models.py
+++ b/nummi/main/models.py
@@ -3,15 +3,33 @@ from django.db import models
 from django.forms import ModelForm
 
 
+class Category(models.Model):
+    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
+    name = models.CharField(max_length=256)
+    parent = models.ForeignKey("self", on_delete=models.SET_NULL, blank=True, null=True)
+
+    def __str__(self):
+        if self.parent:
+            return f"{self.parent}>{self.name}"
+        else:
+            return f"{self.name}"
+
+
 class Transaction(models.Model):
     id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
     name = models.CharField(max_length=256)
     description = models.TextField()
     value = models.DecimalField(max_digits=12, decimal_places=2)
     date = models.DateField()
+    category = models.ForeignKey(
+        Category, on_delete=models.SET_NULL, blank=True, null=True
+    )
 
     def __str__(self):
-        return f"{self.date} {self.name}: {self.value}€"
+        res = f"{self.date} {self.name}: {self.value}€"
+        if self.category:
+            return f"{res} ({self.category})"
+        return res
 
 
 class TransactionForm(ModelForm):