The bill titled "An Act promoting fair tax treatment for zero-emission vehicles" aims to amend existing tax laws in Massachusetts to provide more equitable tax treatment for zero-emission motor vehicles. Specifically, it proposes changes to Chapter 60A and Chapter 64H of the General Laws. In Chapter 60A, a new provision will establish that the excise tax for zero-emission vehicles purchased before January 1, 2035, will be based on the lesser of the actual list price or the median list price of comparable internal combustion engine vehicles. This applies to vehicles classified in classes 3 through 8 as defined by the Federal Highway Administration.

Additionally, the bill amends Chapter 64H to state that the retail sales tax on zero-emission vehicles purchased before January 1, 2035, will similarly be calculated based on the lesser of the actual sales price or the median sales price of internal combustion engine vehicles of the same class, type, and year of manufacture. These amendments are intended to encourage the adoption of zero-emission vehicles by making them more financially accessible through fairer tax assessments.