When must an MLB runner retouch a passed base or tag up after a fly ball?

Returning after passing a base

The 2026 rule defines a passed base by the runner’s position: both feet must be on the ground beyond the base’s back edge, or beyond the edge in the direction the runner is advancing. If a runner turns back after passing a base, the runner must retouch that base before trying to advance again. When a runner is required to return, passed bases are retouched in reverse order unless the ball is dead under a rule that permits a direct return to the original base.

The threshold matters because merely leaning or stepping around a base is not the rulebook’s stated test for having passed it. Appendix 6 illustrates the rule for movement toward and away from each base; this guide uses the rule’s wording rather than reproducing those diagrams.

Leaving on a fly ball

For a fly ball, the rulebook permits a runner to leave the base at the instant the first fielder touches the ball. A catch can be completed later: the catch definition allows a ball to be held after a juggle, provided it is finally secured before it touches the ground. The first fielder touch and the later completion of a catch are different moments.

That distinction resolves a common mix-up. A runner who remains on the base until first fielder touch and then leaves has met the departure timing, even if a bobble delays the catch. The later catch alone does not make that runner return and touch the base again.

If the runner leaves too early

After a fly is legally caught, a runner who left before the first fielder touched it must return to and retouch the original base before advancing. The runner must make contact with the base and start forward from that contact; taking a flying start from behind the base does not satisfy the retouch requirement. The defense may appeal by tagging the runner or original base before the retouch. Under Rule 5.09(b)(5), that appeal is unavailable after the first following pitch or any play or attempted play. The appeal depends on the required sequence and a timely appeal, not merely on a claim that the runner left early.

A ball that is not legally caught is not a caught-fly tag-up play. Other rules can still govern the live ball, a return to a passed base, or a dead-ball situation.

Use the rulebook that governs the game

This explanation follows the Office of the Commissioner of Baseball’s Official Baseball Rules, 2026 Edition. The book does not state a separate day-level publication or effective date. Check the rules and ground rules for the competition being played; this page does not decide a real play or replace an umpire’s judgment.

Two different departures

In a fictional example, a runner at third stays in contact with the base until a fielder first touches a high fly, then leaves. The ball bobbles but is secured before touching the ground. The later catch does not alone require a second touch of third. In a separate fictional play, a runner leaves before first fielder touch and has not retouched the original base when the defense tags the runner or base after a legal catch; that sequence may support an appeal. On a ground ball, another runner retreats only after both feet are on the ground beyond the specified edge of a base, then must retouch it before advancing. These examples do not decide any real play.

Related questions

Sources and further reading

• Office of the Commissioner of Baseball, Official Baseball Rules, 2026 Edition: Rule 5.06(b)(1), Definitions of Terms (RETOUCH and CATCH), Rules 5.09(b)(5) and 5.09(c)(1), and Appendix 6. Checked 2026-10-15; the rulebook states no separate day-level publication or effective date.