This might give you an idea. Data is from 2009 and gathered by the IRS and the city comptroller’s office.

NYC Federal AGI	Count	Pct
$200,000 to $500,000	89,197	2.50%
$500,000 to $1,000,000	19,333	0.60%
$1,000,000 to $5,000,000	12,996	0.40%
$5,000,000 or more	1,916	0.10%
Sub-Total	123,442	3.53%
Total Population	3,497,930

Unfortunately the data I was looking at wasn’t granular enough to show the exact breakpoints that correspond to the fiscal cliff deal (aka American Taxpayer Relief Act of 2012). However, you get the sense that there are close to 120,000 tax filers, about 3.5% of the city’s taxpayers, that may notice a significant increase in their tax bill (income taxes, AMT, less deductions/exclusions, medicare contribution, capital gains, et al). The exact impact will vary I suppose based on certain variables and degree of creative interpretation of tax laws. I would guess the income distribution in this town hasn’t changed radically since 2009…

Doesn’t this city have more than 8 million people?

I understand that many people don’t have to pay federal income taxes based on age, income, and filing status. For example students making nothing or next to nothing, seniors living on social security, etc. According to Wikipedia 18.5% of New Yorkers are below the Federal poverty line (about 1.5 million people). Another site indicates about 3.5 million NYers are 19 years old or younger, and maybe 950,000 or so seniors (65 and up). Wonder if that is the bulk of the difference…