Every year, IRS closes e-file for individual 1040 filers at a certain point of time in the year following the most recent tax year. IRS just closed e-file for 2017 1040s on Nov 17 (even if the taxpayer is in a presidential declared disaster area).
2017 1040s filed from today onward must be done on paper through the mail. This is also why ‘catch-up’ returns often must be paper-filed.
In contrast, three years of corporate returns can be e-filed – two years prior and the current year.
As well, IRS never allows e-file for certain types of return reporting, such as ones claiming a refund of 1042-S or 8288-A over-withholding or rental property returns with gross rents that report no income.