The overall pricetag for the Circle Line would likely be in the range of $14.5B - $18.7B. This was determined by using an average cost per mile range of $850M - $1.1B.
Everyone in Massachusetts would need to do their part and pay a portion of the cost. That means individuals, corporations, non-profits, communities - everyone.
The method to pay for this project would be 5-pronged:
Cost
1. Federal Government
Under the Federal "New Starts" program, the Federal Government would pay for half of the Circle Line. Roughly $7.2B - $9.4B would come from the Feds.
2. Individual Income Assessment
All individuals living in Eastern Massachusetts would pay a special assessment in their annual state income tax return.
For those living in Boston, Brookline, Cambridge, and Somerville (those benefiting most from the Circle Line), the assessment would be an additional 2% income tax per year for 3 years. This amounts to $1.3B.
For those living in the rest of the ~170 cities and towns serviced by the MBTA, the assessment would be an additional 1% income tax per year for 3 years. This amounts to $3.2B.
3. Corporate Assessment
All businesses that pay corporate income tax in Massachusetts would pay a special assessment in their annual taxes. The assessment would be an additional 1.5% above the standard Corporate Income Tax Rate of 8%. The assessment would be levied for 3 years. This amounts to $1.0B.
4. Non Profit Assessment
All non-profit institutions (hospitals and universities) in the Circle Line communities of Boston, Brookline, Cambridge, and Somerville would pay a special assessment of $50K per year for 3 years. This amounts to $5.1M.
5. State Government
The remaining amount would be paid for by the State of Massachusetts, either through reserves or the sale of bonds. Roughly $1.1B - $3.2B would come from the State.