It is confirmed and Official

[Strict]

I thought that you still expend chakra even if you have the EMS.

This Chakra tax vanishes almost completely. Remember how Madara, once he gained the EMS, fought the Senju for 24 hours. And while the normal Susanoo extremely strains your eyes and Chakra, an EMS user is easily able to summon a Susanoo of titanic proportions, without making light of any Chakra loss. So a MS user couldn't even bear the Chakra loss of such a huge Susanoo.

 

[LustyLover]

This Chakra tax vanishes almost completely. Remember how Madara, once he gained the EMS, fought the Senju for 24 hours. And while the normal Susanoo extremely strains your eyes and Chakra, an EMS user is easily able to summon a Susanoo of titanic proportions, without making light of any Chakra loss. So a MS user couldn't even bear the Chakra loss of such a huge Susanoo.

I was led to beleive that he fought for so long because he had huge chakra reserves to begin with. When Sasuke got EMS his Susano'o wasn't as big as Madara's, and he still used chakra. I believe you could only maintain it longer because it's less of a strain on the eyes.

 

[Strict]

Of course he is using Chakra for his techniques, but the Chakra tax isn't worthy to be mentioned. And alter, he gained the perfect Susanoo. Itachi said, that with the EMS, you will gain true power. And I think it's the perfect Susanoo.