Yes, KICKBACK is a Scrabble word!

Letter values in Scrabble US: K 5, I 1, C 3, K 5, B 3, A 1, C 3, K 5.

Is it a valid word?

KICKBACK is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

a commercial bribe paid by a seller to a purchasing agent in order to induce the agent to enter into the transaction