Does deathtouch work with trample?

Normally, a trampling attacker must assign lethal damage to each blocker before it can assign excess damage to the defending player or planeswalker (CR 702.19b). Lethal damage is defined as damage equal to a creature's toughness minus any damage already marked on it (CR 119.6).

Deathtouch changes what counts as "lethal": any amount of damage from a deathtouch source is considered lethal (CR 702.2b). So a creature with both trample and deathtouch only needs to assign 1 damage to each blocking creature to satisfy the trample requirement.

For example, a 6/6 with trample and deathtouch blocked by two 5/5s only needs to assign 1 damage to each blocker (2 total), then can assign the remaining 4 damage as trample damage to the defending player.

This interaction is explicitly addressed in CR 702.19b, which states that when determining how much damage must be assigned to a blocker, deathtouch is taken into account.