When you print your tax return for mailing it will print with a page of mailing instructions that will tell you what addresses to put on the envelopes for federal and state returns--which go in separate envelopes to separate adresses.
When you mail a tax return, you need to attach any documents showing tax withheld, such as your W-2’s or any 1099’s. Use a mailing service that will track it, such as UPS or certified mail so you will know the IRS/state received the return.
Federal and state returns must be in separate envelopes and they are mailed to different addresses. Read the mailing instructions that print with your tax return carefully so you mail them to the right addresses.
Note: Mailed returns are taking quite awhile for processing because the IRS is backlogged. Your mailed return will not be opened right away.
Per the IRS website IRS Operations During COVID-19: Mission-critical functions continue:
IRS operational status and alternatives
Processing Delays for Paper Tax Returns: Taxpayers should file electronically through their tax preparer, tax software provider, or IRS Free File.
We’re experiencing delays in processing paper tax returns due to limited staffing. If you already filed a paper return, we will process it in the order we received it.
Do not file a second tax return or contact the IRS about the status of your return.
When the IRS finally opens its mail and begins to process mailed returns you can check the status on the IRS site. https://www.irs.gov/refunds