1.   Accrual, basis and nature of right

a.    It arises by operation of law upon payment of the guarantor
b.   It is not a contractual right
c.    The  guarantor  is  subrogated  by  virtue  of  the payment to the rights of the creditor

2.   When  right  not  available—it  cannot  be  invoked  in  those cases where the guarantor has no right to be reimbursed

Art. 2067. The guarantor who pays is subrogated by virtue thereof to all the rights, which the creditor had against the debtor.
If  the  guarantor  has  compromised  with  the  creditor,  he cannot demand of the debtor more than what he has really paid. (1839)



> Transfers to the person subrogated, the credit with all the rights  thereto  appertaining  either  against  the  debtor  or against third persons, be they guarantors or possessors of mortgages,    subject    to    stipulation    in    conventional subrogation