The Tax1099 integration isn’t an integration in our traditional sense, because you don’t install it on the Integrations > Add/Remove page.
This integration works in conjunction with the IRS FORM 1099-MISC/NEC report on the Reports > Compliance Tools page. After you generate the report, click the white print/export button at the bottom. In the menu that pops up, you’ll see an option for a Tax1099.com Export.
After downloading the 1099 export from ISP, navigate to your Tax1099 account and upload the file there. From there, you can send them to your recipients and the IRS.