Can you use convoke to tap creatures with summoning sickness?

Convoke lets you tap creatures you control to help pay for a spell's mana cost, reducing the cost by one mana per creature tapped (or more if the creature matches the spell's color). However, tapping a creature as a convoke payment is still an act of tapping it as a cost, which means the normal rules about tapping apply.

Under CR 302.6, a creature cannot attack or use activated abilities with the tap symbol in their cost if it has been under your control since the beginning of your most recent turn — commonly called 'summoning sickness.' CR 702.51b specifically states that tapping a creature for convoke is a cost, and CR 302.6 prohibits tapping a creature for costs if it is affected by summoning sickness.

The key rule is CR 302.6: a creature can only be tapped for costs (including convoke) if you have controlled it continuously since the start of your most recent turn. If you just played a creature this turn and it has summoning sickness, you cannot tap it to convoke a spell.

Concrete example: You cast a 2/2 creature on your turn. Later that same turn, you want to cast a convoke spell and tap your new 2/2 to help pay for it. You cannot do this — the 2/2 has summoning sickness and may not be tapped as a convoke cost. If you wait until your next turn, you can freely tap it for convoke.

Note: Creatures with vigilance or abilities that say they can tap without being affected by summoning sickness are exceptions, but by default summoning sickness blocks convoke use.