If you compare trading service levels you can see a table that lists all of the benefits of 'Active Trader Services' and 'Active Trader VIP' status and one of them is "Free TurboTax® Premier Online". If you don't meet the qualifications for one of these levels it says you qualify for a discount on TurboTax (does not specify which version).
Qualifications
Active Trader Services
Trades: 120+ stock, bond, or option trades in a 12-month period
Minimum balance: Maintain $25,000 in assets across your Fidelity accounts
Active Trader VIP
Trades: 500+ stock, bond, or option trades in a 12-month period
Minimum balance: Maintain $1,000,000 in assets across your Fidelity accounts