Short answer. The court itself fixes each person's share. The Revised Penal Code directs that where two or more people are civilly liable for a felony, the courts determine the amount for which each must respond, so the judgment should state a figure for each accused rather than one lump sum.
What the law says
If there are two or more persons civilly liable for a felony, the courts shall determine the amount for which each must respond.
Revised Penal Code, Article 109 — Apportioning Civil Liability. Read the full provision →
Apportionment is the court's job, not the victim's
Article 109 puts the task squarely on the court: it shall determine the amount for which each must respond. A complainant is therefore not expected to work out afterwards who owes what, and the accused are not left to negotiate it among themselves. The share is not always an equal split. Participation in the felony is graded, and the Code apportions liability by class — principals, accomplices and accessories are treated differently, with the heavier burden falling on those who took the larger part. Two co-accused convicted in different capacities can end up responsible for very different amounts out of the same total.
Solidary within a class, subsidiary across classes
The Code does not stop at fixing shares. Persons liable in the same class answer solidarily among themselves, meaning the victim may collect the whole of that class's portion from any one of them, leaving that person to recover from the others. Across classes the liability is subsidiary: if the principals cannot pay, the burden moves to the accomplices, and then to the accessories. The practical effect is that an accused with assets can be made to pay far more than his own arithmetical share, and then has to chase his co-accused. Anyone who pays should therefore document the payment carefully, because the right to reimbursement depends on proof.
What the shares cover
The amounts being divided are the heads of civil liability the Code recognises — restitution of the thing taken, reparation of the damage where the thing can no longer be returned, and indemnification for the further losses the offence caused. Restitution is a duty of the offender even if the item has passed to a third person, subject to the protections the law gives certain buyers. What the article does not do is make anyone liable who was not adjudged liable at all: acquittal on the ground that the accused did not commit the act generally carries the civil liability with it, though an acquittal on reasonable doubt may leave a civil claim alive.
Others who may be reached
Liability does not always stop with the persons convicted. The Code makes certain innkeepers, tavern keepers and employers subsidiarily liable in the situations it describes, in the employer's case for felonies committed by employees in the discharge of their duties, and only once the employee's insolvency is shown. That is a narrow route, not a general rule that a company pays for its staff's crimes. If you are a complainant, ask that the judgment specify each accused's share, because a vague award is hard to execute; if you are an accused, check whether the share assigned to you matches the capacity in which you were convicted. Take advice on the specific judgment rather than relying on this general description.