Quick answer: The clubhead moves inside the hand line within the first 12 inches; the forearms rotate early.
What it does to the ball
Open face at the top → slice pattern; loss of compression and roughly 8-12 m of carry.
Root causes (by frequency)
Early forearm rotation instead of a connected shoulder turn
Starting the swing with the hands, not the torso (broken one-piece takeaway)
How to fix it
One-piece takeaway: shoulders, arms and club move back together; keep the clubhead outside your hands for the first 12 inches
Drills that fix it
One-piece takeaway with alignment stick · 10 min · 20 reps
Fix the inside takeaway that opens the face Lay a club on the ground parallel to your target line. Move the clubhead outside your hands for the first 12 inches, without rotating the forearms.
Frequently asked questions
What is "Inside takeaway" in the golf swing?
The clubhead moves inside the hand line within the first 12 inches; the forearms rotate early.
What does inside takeaway do to the ball?
Open face at the top → slice pattern; loss of compression and roughly 8-12 m of carry.
How do you fix inside takeaway?
One-piece takeaway: shoulders, arms and club move back together; keep the clubhead outside your hands for the first 12 inches
Sources
Ben Hogan — Five Lessons: The Modern Fundamentals of Golf