The tax filing PIN cannot be used to file the 941 forms. To electronically file these forms you will need to use different PIN information.
When filing the 941 forms, you have the option of filing as a taxpayer or reporting agent. If filing as a taxpayer, a 10-digit PIN will be required to electronically file the forms. To electronically file the forms as a reporting agent it will require a 5-digit PIN and a 6-digit EFIN.