Just an FYI for those individuals who have filed their 2019 tax returns by the new original due date of 7/15/2020: You should expect some interest as well.
The IRS is required to pay interest on refunds if the refund is issued more than 45 days after the original due date. In the case of a disaster related change in due date like we just had, interest will be paid, calculated from the 4/15/2020 original filing date through the date of refund, provided that the return was timely filed by the new original due date of 7/15/2020.
Note that only individual tax returns are entitled to this interest. Businesses are not eligible.
Final note: interest received will be taxable income in the year received. Be sure to give your tax preparer your 1099-INT, which you will receive if the amount of interest you receive is greater than $10.