Short answer. The usufructuary. Article 596 puts annual charges and taxes, and those considered a lien on the fruits, at his expense for the whole time the usufruct lasts. The owner bears only taxes imposed directly on the capital, which is a different and much rarer category.
What the law says
The payment of annual charges and taxes and of those considered as a lien on the fruits, shall be at the expense of the usufructuary for all the time that the usufruct lasts.
Civil Code, Article 596 — Annual Charges and Taxes. Read the full provision →
The dividing line is annual burden against capital burden
The two articles allocate by nature of the charge, not by who is more able to pay. Anything recurring, anything that is the cost of holding and enjoying the property year to year, belongs to the person enjoying it. Impositions that fall on the capital — on the substance of the property itself rather than on its yearly enjoyment — belong to the owner, because the substance is his and remains his when the usufruct ends. Once that line is drawn, most disputes answer themselves without any argument about fairness.
Neither side is left worse off by fronting the money
Article 597 handles the practical reality that whoever receives the notice tends to pay. If the owner pays a tax on the capital, the usufructuary owes him the proper interest on the sums paid in that character — the owner is not out of pocket for the period during which somebody else was enjoying the property. If the usufructuary advanced those sums instead, he recovers the amount at the termination of the usufruct. So the charge stays where the Code puts it, and payment by the wrong party creates a reimbursement rather than a windfall.
What paying does not buy you
A usufructuary paying the annual tax for many years sometimes concludes that this says something about ownership. It does not. He pays because the Code tells him to, and a tax receipt in his name records who settled the assessment, not who owns the land. The same holds in the other direction: an owner who quietly pays to keep the property from going delinquent has not taken back the usufruct. What is worth watching is the declaration itself, since an entry naming the wrong party is a nuisance to correct later.
Sort out the mechanics early
Delinquency is a serious risk to a property, and it does not care which of you was supposed to pay. Agree in writing who physically files and pays, where the notices are sent, and how proof of payment is shared each year — an owner who never sees a receipt has no way of knowing the obligation is being met. Keep the payment history, because the reimbursement rights in Article 597 are computed from dated receipts, and read the instrument creating the usufruct first in case it allocates these charges differently.