In baseball, “tagging up” means a baserunner must stay on (or return to) their starting base until the ball is first touched by a fielder on a caught fly ball, and only then may they try to advance to the next base at their own risk.

Quick definition

  • Tag up (verb): When a runner “tags up,” they wait on their base until a fly ball is touched by a fielder, then run toward the next base.
  • The runner must touch the base (the “tag”) after the ball is touched; if they leave too early, the defense can throw to that base and double them off.

When does tagging up apply?

Tagging up is only required on:

  • Caught fly balls (in the air)
  • Caught line drives

It does not apply to:

  • Ground balls
  • Balls that bounce before being caught
  • Batted balls that are not caught.

How it works in a play

Imagine a runner on second base with one out:

  1. The batter hits a deep fly ball to the outfield.
  2. The runner takes a lead off the base , watching the ball.
  3. An outfielder touches (and usually catches) the ball.
  4. The runner returns to second , touches it (“tags up”), then runs to third or even home if the ball is deep enough.

If the runner:

  • Leaves before the ball is touched , and the defense throws to second before the runner retouches, the runner is out.

Tagging up and sacrifice flies

One of the most common strategic uses of tagging up is the sacrifice fly :

  • Runner on third base , less than two outs.
  • Batter hits a deep fly ball that is caught.
  • Runner tags up and runs home as soon as the ball is touched.
  • If the runner scores, it’s a sacrifice fly :
    • Batter gets an RBI (run batted in).
    • Runner gets a run scored.
    • Batter is recorded as having made an out.

A sacrifice fly only counts if a run actually scores on the play; advancing from second to third on a caught fly is just an advance on an out, not a sac fly.

Key rules and misconceptions

  • You don’t have to wait for the catch; you only have to wait for the ball to be touched.
    Even a bobble or an “almost dropped” ball that is eventually caught still allows the runner to go once the ball is touched.
  • The force out created by a caught fly ball is removed once the runner retouches their original base; after that, they can advance or return like on any other live ball.
  • Coaches often give signals (hand waves, “tag up” shouts) telling runners whether to:
    • Stay on the base and wait,
    • Go “halfway” (riskier), or
    • Immediately run after the touch.

Common situations where you’ll hear “Tag up!”

  • Runner on third , deep fly to left/center/right field → coach yells “Tag up!” so the runner can score on a sacrifice fly.
  • Runner on second , very deep fly → coach may say “Tag up and go for third” if the ball is deep enough.
  • Less than two outs is the key condition: if there are two outs, runners usually just run on contact, because the out is already recorded and the play is live.

Information gathered from public forums or data available on the internet and portrayed here.