The 8-return package of TurboTax Deluxe Online allows you to prepare 8 Deluxe returns. After that, you can prepare 12 more returns, but they will be separate from your 8-return package. You can prepare those additional returns for Free, but it's not based on income, rather it's based on what the taxpayer enters on their return. Please see this TurboTax FAQ for more information: Who can file for free using TurboTax?
In the past you may have used TurboTax Standard CD/Download (for Windows). That allows you to prepare 8 tax returns for filers with net annual income over $25,000, and 12 returns for additional taxpayers with net income below $25,000.