Even if you did not file your income taxes last year you can still file an extension. However, you may need additional information in lue of your tax return AGI to “sign” the electronic filing.
One of the ways you may "sign" your electronic filing with the IRS is by entering information from your prior year tax return. Since you will not have access to this information you will need to use a Self-Select IRS filing PIN to sign your return.
If you do not have or remember your Self-Select PIN (and since you do not have your prior year tax return to either sign your return or generate a new Electronic Filing PIN) you will need to proceed by printing and mailing-in your extension, rather than e-filing.