Do you need to finish it? It is too late to get any refunds for 2020 and before. If you need to file you will have to print and mail your return. If you need to finish or enter more info then you need to switch to the Desktop installed program on a full Windows or Mac computer. You might be able to download the .tax2018 data file to open in the Desktop program.
Even if the 2018 tax form shows a refund, that refund has been forfeited and will not be paid to you. If you owe tax due, you need to pay asap, and then expect a bill for the late filing penalties and interest that have been adding up since 2019.
The only way to file a 2018 return is by mail. Print, sign and date it in ink, and mail it in. What about the years after that? Are you behind in preparing and filing tax returns? You are also too late to receive refunds for 2019 or 2020. You can still receive a refund for 2021, 2022 or 2023 but the returns must be filed by mail.
Each tax year has to be filed separately using the forms for the specific tax year. They cannot be combined in any way--do not even put them in the same envelope when you mail them. Software for past years is available back to 2021. The software for years earlier than 2021 is no longer available. You can use the paper forms to prepare by hand, or you can seek local paid tax help.
It might be better for you to seek local paid tax help in a situation when you are several years behind in filing your tax returns. Do you even have all of the documents you will need to enter and show your income—like your W-2’s and any 1099’s?
Online preparation and e-filing for 2021, 2022, and 2023 is permanently closed.
Note: The desktop software you need to prepare the prior year return must be installed/downloaded to a full PC or Mac. It cannot be used on a mobile device.
To file a return for a prior tax year
If you need to prepare a return for 2021, 2022, or 2023 you can purchase and download desktop software to do it, then print, sign, and mail the return(s)
https://turbotax.intuit.com/personal-taxes/past-years-products/
You may also want to explore purchasing the software from various retailers such as Amazon, Costco, Best Buy, Walmart, Sam’s, etc.
Remember to prepare your state return as well—if you live in a state that has a state income tax.
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/state received the return.
Federal and state returns must be in separate envelopes and they are mailed to different addresses. Read the mailing instructions that print with your tax return carefully so you mail them to the right addresses.