Although taxpayers and practitioners can file forms W-2, 1099, WT-6 and WT-7 electronically, the IRS will not accept XML returns until the service providers have received the agency’s approval.
All software providers that generate XML returns for the W-2, 1099, WT-6, WT-7 as well as IRS Data Exchange files must complete the Wisconsin Provider Software Letter of Intent and receive approval through the department’s testing program.
Find more information here.