The 2025–2026 NYS Inflation Refund checks are generally not taxable for New York State personal income tax purposes, as they are considered a return of previously paid sales tax. However, for federal income tax purposes, the refund may be considered taxable income if you itemized deductions on your federal return and received a tax benefit from that deduction in a previous year.
From what I can find online, the NYS inflation refund checks appear to be taxable at the federal level, for everyone. Per the NY.gov site, link below, the refund was based on your income and filing status, not whether you itemized deductions. Per several articles online, two links below, the state could have structured the refund program differently to potentially avoid federal taxation, but they didn't do so for whatever reasons. I may be mistaken, but that's how I'm interpreting it.