The distinction between Joint and Solidary Obligations are very important in civil law. The following shows the basic differences between the two obligations:
JOINT OBLIGATION - it is one wherein a debtor is obliged to pay a portion of the full amount of debt that corresponds only to his share. Likewise, the joint creditor can only demand a portion of the full amount that corresponds to his share.
For an instance, A and B contracted a loan amounting to P10 million from X. A received a share amounting to P6 million while B received an amount equal to P4 million. When the obligation came due, A is only obliged to pay an amount corresponding to his share of the loan, which is P6 million.
SOLIDARY OBLIGATION - refers to a kind of obligation wherein either one of the creditors has the right to demand full compliance of the obligation from either one of the solidary debtors.
For an instance, in a loan contract, A and B borrowed an amount equal to P10 million and agreed to pay the said amount solidarilly to X and Y, who are also solidary creditors. A received P6 million while B received P4 million. When the contract came due, either X or Y can compel any of A and B to pay the whole amount of P10 million, regardless of their share. The one who paid the whole amount will just reimburse the share received by the other debtor.
Any solidary debtor may be compelled to pay the whole amount, not only his share, whether or not he benefitted from the said debt. Solidary obligation is never presumed. The main reason for this is that solidarity gives huge right to the creditor to demand full compliance of the obligatiom from any of the debtors.
The use of the term "solidary" is not required by law to make a contract or agreement solidary. It is enough that the parties include other terms which also mean the same thing, such as "jointly and severally".
The three sources of solidarity are: (1) by law; (2) by stipulation of the parties to the contract, and; (3) by the nature of the obligation.