Yes, QUALIFYING is a Scrabble word!

Letter values in Scrabble US: Q 10, U 1, A 1, L 1, I 1, F 4, Y 4, I 1, N 1, G 2.

Is it a valid word?

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

the grammatical relation that exists when a word qualifies the meaning of the phrase
success in satisfying a test or requirement

prove capable or fit; meet requirements
pronounce fit or able
make more specific
make fit or prepared
specify as a condition or requirement in a contract or agreement; make an express demand or provision in an agreement
describe or portray the character or the qualities or peculiarities of
add a modifier to a constituent

Also: measure up.

Not playable in Scrabble US: CHARACTERISE.