I received a 1099 for last tax year, but I didn't receive my payment until this tax year – Singletrack Accounting

This is a situation that can occur when the year ends:

a business makes a check payment to a 1099 service vendor on the last few days of the year, let's say December 28th. The payment is on the businesses' books dated in an ending tax year
the 1099 service vendor receives their check payment on the first few days of the new year, let's say January 2nd. The service vendor records their payment on their books dated in the new year.

The business must issue the service vendor's 1099 in the amount they paid out, the amount on their books for the ending year.....even though the service vendor's books will record receiving their 1099 income in a different year.

The IRS knows this will happen and handles the situation with the principle of "Constructive Receipt".

The proper way for the 1099 vendor to report their income is to report it in the correct year for them - the year they received the payment. However, you will still have to enter the 1099 that you received as is (because the 1099 is correct from the issuer perspective) and then make an adjustment for your Schedule C for the amount - labeled as "Not constructively received - reportable in (next tax year)" You can make the adjustment by entering this as a negative income number or as an expense.