The IRS sent me a CP-2000, which said I didn’t file 1099 income for $1300. I never got a 1099 from the client. How did the IRS come up with this amo

Taxpayers must always remember that employers, banks, brokers, clients, etc, file informational returns to the IRS in order to substantiate their own tax deductions.

The IRS matches amounts reported on tax returns with the information returns.
This computer matching begins after the original return due date.

Call the IRS, if you don’t know already, which of your clients turned in the 1099 income. If you received the income, check with your tax professional before signing and returning to the IRS.

If you did not complete work for the client and never received the $1300 – contact the client and ask for clarification and that the information be corrected with the IRS

For further clarification visit the irs.gov website: keyword: cp 2000