Colorado State Income Tax 2026: 4.4% Flat Rate

At 4.4% flat, Colorado's income tax is competitive with many states while remaining well below high-tax states like California (13.3%), New York (10.9%), and Oregon (9.9%). On a $150,000 salary, Colorado state income tax is $6,600. This is roughly $4,500 less annually than Oregon on the same salary, and $6,400 less than California. Denver has a cost of living index of approximately 1.10 — above the national average but well below coastal tech markets.

The TABOR (Taxpayer's Bill of Rights) caveat is important to understand. Colorado's constitution requires that when state tax collections exceed a certain threshold, the excess must be refunded to taxpayers — often implemented as a temporary rate reduction or direct refund check. This occurred in 2022 and 2023, briefly lowering the effective rate. The 4.4% baseline rate is the legislated rate for 2026, but taxpayers should note that their actual effective rate could be slightly lower if TABOR refunds are triggered during the year. This is a feature unique to Colorado and means the rate should be modeled as '4.4% or potentially lower' rather than a fixed ceiling.

Denver has emerged as one of the most important secondary tech markets in the US, with significant operations from Google, Amazon, and a growing startup ecosystem. At COL index 1.10, Denver is more affordable than Seattle (1.35), Boston (1.47), or San Francisco (1.74), while offering a 4.4% flat income tax versus Washington's 0%. The combination of moderate cost of living, outdoor amenity premium, and a competitive tax environment makes Denver a frequently evaluated alternative to coastal tech hubs.