Dodge: when the benefits apply and end

SRD 5.2.1 · Actions

At the table

1. Until the start of your next turn, incoming attack rolls have Disadvantage if you can see the attacker.
2. During that period, make Dexterity saving throws with Advantage.
3. Lose these benefits if you become Incapacitated or your Speed is zero.

Example decision

A character takes Dodge and is then Grappled, setting Speed to zero. Do the Dodge benefits remain until the next turn?

No; Speed zero ends those benefits.

Dodge explicitly loses its benefits if Speed is zero, which Grappled imposes. The ordinary expiry is therefore not the only way it stops helping. A separate condition can still affect incoming attacks or saving throws, but those changes should be recorded under that condition rather than attributed to the lost Dodge benefits.

Watch for this mistake

The attack-roll protection requires seeing the attacker. Do not apply it blindly to every incoming attack. That visibility clause is attached to the attack benefit; the Dexterity-save benefit is stated separately.

Ask the table

Can the dodging creature see this attacker, and is its Speed still above zero?

Source rule

If you take the Dodge action, you gain the following benefits: until the start of your next turn, any attack roll made against you has Disadvantage if you can see the attacker, and you make Dexterity saving throws with Advantage. You lose these benefits if you have the Incapacitated condition or if your Speed is 0.

Source: SRD 5.2.1, 181. Online guide.