Creating invoice assignment rules An invoice assignment rule is used to determine which payables processor to assign to a specific invoice. Select Financials > Payables > Payables Setup > Invoice Assignment Rules. Click Create. Specify a Vendor Group, Name and Description. Specify this information: Invoice Assignment Rule Specify a custom group for the invoice assignment rule. Resource Specify a resource for the invoice assignment rule. Processing Team Select an approval team for processing the assignment rule. Click Save.