When did you mail it? Did you get a tracking number from the Post Office? That's the only way. If you mailed it in 2020 the IRS is behind in opening the mail due to the Covid-19.
They were closed for several months and didn't start opening the mail until June that's been stacking up. An IRS spokesperson said that they have about 11 million pieces of unopened mail. The IRS says.."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." So you have to keep waiting.
See this IRS page for the latest information
https://www.irs.gov/newsroom/irs-operations-during-covid-19-mission-critical-functions-continue
