So after some googling I found the link below which discusses the topic. It seems in New York State that once your income goes above a certain level (c.$105k) then the marginal income tax rate is applied to your whole income. This is also confirmed by the tax guidance document that NYS issues where the calculation tables purport to show detail workings but then basically tell you to skip all that if your income is above a certain level and just to apply the marginal rate.
https://www.bogleheads.org/forum/viewtopic.php?t=192321
