As of this morning, March 18, the following are the reports for filing deadlines and extension changes for the federal government as well as Maryland and Delaware:

Federal

Individual filings must be completed by April 15 but payment of taxes can be made until July 5 without penalty.  Note that there is confusion on if the WhiteHouse plans to extend the filing deadline and clarification is expected.
Sources: WhiteHouse Briefing and CPA Advisor

Maryland

Individual Income Tax Deadline extended to July 15.
Source: News Release_ Maryland Income Tax Deadline Extended to July 15, 2020

Business Tax Filing for certain businesses extended to June 1s  SEE DETAILS
Source: News Release_ Franchot Announces Extension of Business Tax Filing Deadlines

Delaware

No changes reported to filing deadlines at this time.
Source: Delaware.gov website