On March 21, the Pa. Department of Revenue announced that Pennsylvania income tax returns and income tax payments for the year 2019 will be deferred to July 15. This is similar to the previous announcements by the Internal Revenue Service for federal income tax returns and payments.
Estimated income tax payments for the first and second quarters of 2020 are also deferred to July 15. (The federal deferral only applies to first quarter estimated tax payments.)
There is a web page for current Department of Revenue alert details for coronavirus information.
For information on filing deadlines for other states, see this chart from the American Institute of Certified Public Accountants.