Sorry if you missed that train. But you can still prepare your late return online.
You cannot e-file a prior year tax return. However, you can prepare prior year returns on PriorTax and send your printed return copy in the mail, to the IRS.
You can only e-file a “current year” tax return between mid-January when e-file opens and mid-October when it closes, the year after the tax year in question.
Each year the IRS shuts down their e-file system come mid-October. This is why you will need to send in a physical copy of your return to the IRS.