Massachusetts Bay Transportation Authority
Services = > Funding > Fares and fare collection > Subway and bus

All subway trips (Green Line, Blue Line, Orange Line, Red Line, Ashmont-Mattapan Line, and the Waterfront section of the Silver Line) cost $2.40 for all users. Local bus and trackless trolley fares (including the Washington Street section of the Silver Line) are $1.70 for all users.
Paying directly with cash is only available on buses, Green Line surface stops, and the Ashmont-Mattapan Line; from 2007 to 2020, the higher CharlieTicket price was charged.
All transfers between subway lines are free with all fare media, without the need to pass through fare control (except when continuing in either direction at Ashmont Station). Passengers using CharlieCards can transfer free from a subway to a bus, and from a bus to a subway for the difference in price ("step-up fare"). CharlieTicket holders can transfer free between buses, but not between subway and bus, except free subway transfers are given for the Silver Line at Airport station and SL4/SL5 branches.
The MBTA operates "Inner Express" and "Outer Express" buses to suburbs outside the subway system. Inner Express bus trips cost $4.25; Outer Express trips cost $5.25. Free transfers are available to the subway and local buses with a CharlieCard, and to local buses with a CharlieTicket.
CharlieTickets are available from ticket vending machines in MBTA rapid transit stations.  CharlieCards are not dispensed by the machines, but are available free of charge on request at most MBTA Customer Service booths in stations, or at the CharlieCard Store at Downtown Crossing station.  As given out, the CharlieCards are "empty", and must have value added at an MBTA ticket machine before they can be used.
The fare system, including on-board and in-station fare vending machines, was purchased from German-based Scheidt and Bachmann, which developed the technology. The CharlieCards were developed by Gemalto and later by Giesecke & Devrient. In 2006, electronic fares replaced metal tokens, which had been used on and off by transit systems in Boston for over a century.
Upon introduction in 2007, fares for reloadable CharlieCard contactless smart cards were substantially lower, to encourage riders to use them. The alternative magnetic stripe CharlieTickets were not as durable (and so could only be loaded once), were slower to read, and required maintenance of machines with moving parts.
In 2020, the MBTA started implementation of its "Fare Transformation" program, reducing cash-on-board and CharlieTicket prices to the CharlieTicket level. In the fall of that year, the agency started upgrading a portion of faregates at all stations to accept only contactless cards, in anticipation of the phase-out of paper CharlieTickets, which occurred on March 31, 2022. The gates also feature a optical reader, which is currently unused but is capable of scanning QR codes or bar codes, such as those generated by the mTicket app.
Installation of upgraded fare vending machines is expected to be complete by spring 2022, allowing riders to purchase CharlieCards and the new tappable CharlieTickets at any rapid transit station. These also serve as fare validation points for proof of payment on the Green Line Extension.
Starting July 1, 2022, two free transfers will be given to CharlieCard stored-value users for all combinations of subway, bus, and express bus rides.