Short answer. You do, as the debtor, unless your contract says otherwise. Article 1247 provides that the extrajudicial expenses required by the payment shall be for the account of the debtor, absent any different stipulation. So transfer, delivery, and similar fees needed to make the payment are yours to bear by default.
What the law says
the extrajudicial expenses required by the payment shall be for the account of the debtor
Civil Code, Article 1247 — Expenses of Payment. Read the full provision →
The debtor pays the cost of paying
Article 1247 sets the default clearly: the extrajudicial expenses required by the payment shall be for the account of the debtor. The obligation is to deliver what you owe to the creditor, and the ordinary costs of getting it there fall on you, the one who owes. Think of the fees needed to actually hand over the payment: transfer charges, delivery or shipping of the thing owed, the cost of counting or packaging, and similar out-of-court expenses. The law reasons that it is the debtor's job to pay, so it is the debtor's job to cover the expense of performing that duty. The creditor is entitled to receive what is due without shouldering the cost of its delivery.
Unless it is otherwise stipulated
The rule is only a default; it yields to the parties' agreement. The article opens with the words unless it is otherwise stipulated, meaning you and the creditor are free to divide these costs however you like in your contract. You might agree that the creditor bears delivery, or that you split transfer fees, or that a particular charge is on his account. When the contract speaks, the contract controls; the article fills the gap only when the parties said nothing. So the first place to look is your own agreement. If it is silent on who pays the cost of making payment, then the default applies and the debtor pays.
Judicial costs follow a different rule
Article 1247 draws a line between out-of-court expenses and court expenses. For anything that goes to litigation, it says that with regard to judicial costs, the Rules of Court shall govern. So if a dispute ends up in court, who pays the costs of the case is not decided by this article but by the procedural rules, which have their own scheme for awarding costs, often against the losing party. Keep the two separate: the fees of simply performing the payment are extrajudicial and are the debtor's by default, while the costs of a lawsuit about it are judicial and follow the Rules of Court.
What this means in practice
In everyday terms, if you owe money or a thing and it costs something to get the payment to your creditor, expect that expense to be yours unless you arranged otherwise. This includes many modern costs: bank transfer charges, remittance fees, or the cost of delivering goods you sold. It does not, however, let a creditor pile on unrelated charges; the article covers expenses required by the payment, meaning those genuinely needed to perform it. Because what counts as necessary, and what your contract says, can both be argued, this is general information. Your written agreement and the nature of each charge decide the specific case.