TurboTax Online is free to start, the final price depends on the forms you need and the complexity of your return. There is a completely free version of TurboTax online available through the IRS free file program, if your income is $36,000 or less. The most cost efficient way to file (if you don’t qualify for free online filing) is usually to buy the desktop version of the program as a CD or download from a discount retailer such as Costco or Amazon. You will want the TurboTax Deluxe Federal plus One Free State version. It should be around $45-$55.
if you are not required to file a 2020 tax return because your income is below the filing limit, then you do not need to file a return. However, the stimulus credit is recalculated on your 2020 tax return and if you qualify for more then you received during the year, the extra credit will be included in your tax refund. So you may want to file this year even if your income is below the filing requirement. Using the online version, you can prepare the tax return to see what the outcome is before actually paying for it.
However, there are no versions of TurboTax that are currently up-to-date to deal with both the first and second stimulus credits. I would check back after January 8 to see if the program covers the stimulus payments correctly.
