It depends, on this one you need to talk both to the SBA and a tax accountant
if the payments made by the SBA are income tax free, then you need to create an Other Income account titled tax free income. Deposit the funds in a cash type account using that tax free income account and then post the payment to the loan from that cash type account
if the payments made by the SBA are taxable, then deposit the funds to the cash type bank account and use Other Income as the source account for the deposit. Then post the payment from the cash type account