Yes, TACTLESS is a Scrabble word!

Letter values in Scrabble US: T 1, A 1, C 3, T 1, L 1, E 1, S 1, S 1.

Is it a valid word?

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

lacking or showing a lack of what is fitting and considerate in dealing with others
revealing lack of perceptiveness or judgment or finesse