Apparently Maryland has extended their filing season to July 15.
https://content.govdelivery.com/bulleti ... _WIDGET_C7
As a practical matter, this doesn't have any real impact inasmuch as the Federal deadline hasn't changed as far as I can tell. While there are some gymnastics required to finish a Maryland return after the Federal return is complete, they aren't onerous so there isn't a compelling case to delay filing for most people. One can file and delay the payment to July 15 if the timing of the payment is at issue.
2021 tax year filing deadline extended in MD
2021 tax year filing deadline extended in MD
Don't trust me, look it up. https://www.irs.gov/forms-instructions-and-publications