he can file late by filing and paying late will subject him to penalties and interest in addition to the taxes.
What if I do not file my tax return?
https://ttlc.intuit.com/questions/2572308-what-happens-if-i-don-t-file-my-taxes
You have 3 years to file to get a refund. No time limit if you owe. What year does he need to file? You can't add it to a new year. You have to file each year separately.
How to file a prior year
https://ttlc.intuit.com/community/using-turbotax/help/how-do-i-prepare-a-prior-year-tax-return/00/25984
You can only buy the download for prior years. You have to buy a separate program for each year. They only sell the last 3 years. You need a full Windows or Mac computer to install it on. Buy the download here
https://turbotax.intuit.com/personal-taxes/past-years-products
Or you can get the blank forms from the IRS and fill them out by hand for free. I have links to all the year.
You have to print and mail prior year returns. When you mail a tax return, you need to attach any documents showing tax withheld, such as your W-2’s or any 1099’s. Use a mailing service that will track it, such as UPS or certified mail so you will know the IRS received the return. Don’t forget state.
Important! Mail Federal and State in separate envelopes and mail each year in separate envelopes.