Can I file my 2018 tax return on April 29th of 2019 without having an extension?

[pk]

Of course.  You can file anytime before the October 15th. window ( when the software shuts down).  It is only that if you owe any monies to the tax authority ( IRS and/or the State), they may levy interest charges and sometimes penalty.  By having an extension only thing you avoid is "failure to file" penalty but if you do not owe anything , then till Oct. 15th. there is really no major risk of that.

Just go ahead and file as soon as you can

[Anonymous]

you should file as soon as possible even if you're showing a refund.  sometimes the IRS will change a return because of inaccurate or missing items. then you can end up owing and then the penalties will really pile up if you wait til 10/15