I got a 12C letter for IRS I got a 4883C letter from the IRS How do I prepare requested IRS documents for upload

[xmasbaby0]

Did you read those letters carefully?    What do the instructions in the letters tell you to do?   Do the letters say anything about "uploading" documents?    Or do the letters instruct you to mail or fax some information, and/or to call the IRS?

https://www.irs.gov/individuals/understanding-your-letter-12c

https://www.irs.gov/individuals/understanding-your-letter-4883c

[fanfare]

Go to the designated webpage to find out what file types are accepted.

Invariably, .PDF is one of them.

@imelda-ismael52