diff --git a/{{cookiecutter.project_slug}}/tasks.py b/{{cookiecutter.project_slug}}/tasks.py
index be12127..1ad7083 100644
--- a/{{cookiecutter.project_slug}}/tasks.py
+++ b/{{cookiecutter.project_slug}}/tasks.py
@@ -1,6 +1,11 @@
 # type: ignore
+import re
+from pathlib import Path
+
 from invoke import task
 
+PYPROJECT = Path(__file__).parent / "pyproject.toml"
+
 
 @task
 def venv(c):
@@ -42,6 +47,38 @@ def ci(c):
     c.run(f"docker run --rm {image} sh -c '{cmd}'")
 
 
+@task
+def bump(c, part):
+    """Bump version (patch/minor/major), commit, and tag."""
+    if part not in ("patch", "minor", "major"):
+        raise SystemExit("Usage: inv bump <patch|minor|major>")
+
+    result = c.run("git status --porcelain", hide=True)
+    if result.stdout.strip():
+        raise SystemExit("Working tree is dirty. Commit or stash changes first.")
+
+    text = PYPROJECT.read_text()
+    m = re.search(r'version = "(\d+)\.(\d+)\.(\d+)"', text)
+    if not m:
+        raise SystemExit("Could not find version in pyproject.toml")
+
+    major, minor, patch = int(m[1]), int(m[2]), int(m[3])
+    if part == "major":
+        major, minor, patch = major + 1, 0, 0
+    elif part == "minor":
+        minor, patch = minor + 1, 0
+    else:
+        patch += 1
+
+    new_version = f"{major}.{minor}.{patch}"
+    new_text = re.sub(r'(version = ")\d+\.\d+\.\d+(")', rf"\g<1>{new_version}\2", text)
+    PYPROJECT.write_text(new_text)
+
+    c.run(f'git add pyproject.toml && git commit -m "bump version to {new_version}"')
+    c.run(f"git tag v{new_version}")
+    print(f"Bumped to {new_version}")
+
+
 @task
 def clean(c):
     """Preview files to delete (safe mode)."""