TOS Commission Rates

https://www.thinkorswim.com/tos/displayFaq.tos

What are thinkorswim's commission rates?

For Stock orders, you have the choice of 'Per Share Commission' at $.015 per share ($5.00 minimum) OR 'Flat Fee Trading' at $9.95 per trade (market or limit orders; 5,000 shares maximum). For Option orders, you pay the lesser of $2.95 per contract OR $1.50 per contract plus $9.95 (only one $9.95 charge for unlimited spread legs). For Futures orders, you pay $3.50 per mini contract (inclusive of exchange fees).

Commissions on option spreads

If the trade was entered as a spread, there is only one $10 ticket charge regardless of the number of legs associated with that spread, or $2.95 per contract if that's less.