the pandemic hit the IRS hard and for months returns were not being processed and that was coupled with the IRS suddenly have to modify tits programming so 10's of millions of stimulus checks could be issued. to boot returns with certain credits because of the Path Act could not be processed until late February and then the pandemic hit.
here the advice from TT
What to do
You generally have 30 days to respond to an IRS notice, so there's no reason to ignore it. Follow the instructions. It may request more information or ask a specific question. If it's a minor issue and you are confident of the facts, you can respond to the notice yourself. But sometimes, you may need to seek help from a tax professional. The IRS says in its article "Eight Things to Know if You Receive an IRS Notice" that "most correspondence can be handled without calling or visiting an IRS office."
If you filed the tax return with TurboTax, you can take advantage of our free audit support options. Our Audit Support Center walks you step-by-step through responding to an IRS notice.
If you agree with the correction notice
If you make a mistake on your tax return, you may receive a correction notice or an unreported income notice. Compare the IRS adjustments with the information on your tax return. If you agree with the adjustments, you can generally reply to the IRS with a check or money order for the additional taxes due. Write the reference number on the check and send it with the voucher the IRS provides with your notice.
If you do not agree with the correction notice
If you do not agree with the notice, then respond as soon as possible with a written explanation. Explain your reasons for disagreeing and enclose copies of all relevant documents. Mail it to the address on the top left corner, along with the tear-off stub for reference. Start a new folder and keep all correspondence in one place (including copies of your responses to the IRS) for ease of reference. Allow at least one month for the response.
The important thing is to respond—ignoring notices will get you nowhere and could result in additional penalties down the line.
audit support link
https://support.turbotax.intuit.com/irs-notice/audit-support/?TB_iframe=true
