How Come Naruto Never Uses The Chakra Of The Nine Tails?

Naruto first gained the Nine Tails Cloak during training with Killer B, who forcefully extracted his chakra from it. This form appears when Naruto taps into that reserve of chakra. During the war, Naruto gets the light half sucked out and Minato gives him the dark half. The 9tails chakra is only half of what could be used in the entire series. Killer B can transform into the 8 tails at will and be in control as he befriended them. Naruto has befriended the 9 tails, but never transformed into the Nine Tails like he did when he was introduced in the sequel series Boruto: The Next Generations.

Naruto sought to learn how to control Kurama’s power with help from Killer B, the jinchūriki of Gyūki, and unexpectedly, his own mother, Kushina. He transferred his 9 tails chakra to the allied Shinoboi force and used it to fight, but eventually lost control. Naruto Uzumaki, the perfect Jinchuriki of Kurama, can use several forms of the Nine-Tails Chakra Mode, making him the strongest human and Hokage to ever live.

However, Naruto is not allowed to use the Nine Tails chakra due to his Eight Trigrams Seal, which only Naruto and Minato had. He later can combine Sage Mode with his Nine-Tails Chakra mode, making his Sage Mode still useful.

In the last movie, Naruto used the power of the Nine Tails completely instead of using it, losing most of his power stemming from the nine-tailed beast itself.