There are no penalties for filing after the due date if you are receiving a tax refund or have no taxes owed.
If you owe taxes then you should complete and file your tax return, paying the taxes owed, as soon as possible since the penalties and interest continue to accrue for the late filing and late payment. Once the tax return has been filed and the taxes owed have been paid the IRS will send a bill in the mail for any penalties and interest.