How to file your taxes for free as F-1 resident alien
If you are on F visa in the US, you are considered as a non-resident alien for the first 5 calendar years of your stay. Once you pass the substantial presence test, you become a resident alien for tax purposes only. F visa students' days are counted towards the test only after 5 calendar years of their stay. Long story short, an F student is a non-resident alien for the first 5 years and needs to file form 1040NR/1040NR-EZ. They become resident alien for tax purposes in the 6th year and need to file form 1040. Example: Alice came to US in Fall 2015 for her PhD. She would file taxes as non-resident alien for the years 2015-2019, and would become resident alien in 2020. So when filing taxes in the 2021 tax season, she would have to file as a resident alien.
Most schools offer international students tax helps via free tax prep clinics, software (Sprintax/Glacier etc.) subscriptions, and informational seminars. But it is only offered to the NR alien students, so if their studies are not done by the 5th year, they would have to prepare their own taxes when filing as resident alien. So they would need to seek help from any of the commercial tax software or professional tax preparers. These options are not free.
But there is another way. Most students would be eligible for a free tax filing program mandated by IRS, IRS free file. The eligibility condition is based on annual gross income, and usually met by most students who are yet to get a full time job. This works only if the tax filer goes through the links provided in the free file page of IRS (click here). Commercial software try to use people's ignorance about this and often offer a "free" version of their software on their main website. But these free versions do not have most of the components of the full version, and except for extremely basic and simple returns would bar filers with paywalls every now and then. Whereas through free file one can access the full version of the software including all the forms and options. I first came to know about this from a brilliant piece (Episode 8, vol 6: Why Doing Taxes Is So Hard) by comedian Hasan Minhaj on his Netflix show Patriot Act. You can check out the episode here. If you are novice about US tax related frenzies, this is a must watch.
If you qualify for free file offer by at least one of the partner software here, make sure you go to their websites from these links, not their main websites. For example, turbotax free file website is https://freefile.intuit.com/ , but their so called free version website is https://turbotax.intuit.com/personal-taxes/online/free-edition.jsp which you should avoid.
This free file should allow you to file both federal and state taxes* free of cost. If you are eligible for multiple software you can use all of them to compare refund amounts. These softwares are usually very user friendly so even if you know nothing about tax codes and rules you can prepare and file your return in no time!
Note: Turbotax does not support form 1042-S. Non taxable incomes like fellowships, scholarships, awards, tax treaty income etc. are reported on this form so most international students are likely to get at least one 1042-S. But there is a workaround for this, the 1042-S income can be reported as miscellaneous income. For details you can follow the process described here (for tax treaty) or here (for scholarship/ fellowship).
*Free state tax filing availability is different for each software. Check if your state is listed in the offer details.