Short answer. It depends on how the annuity was paid. Article 2025 says the income for the year of death is paid in proportion to the days the person actually lived. But if instalments were payable in advance, the whole instalment that began to run during his life is owed in full.
What the law says
The income corresponding to the year in which the person enjoying it dies shall be paid in proportion to the days during which he lived
Civil Code, Article 2025 — Annuity in the Year of Death. Read the full provision →
What the law says
if the income should be paid by installments in advance, the whole amount of the installment which began to run during his life shall be paid
Civil Code, Article 2025 — Annuity in the Year of Death. Read the full provision →
The annuity ends at death, but the last period needs sorting
A life annuity is paid for as long as a designated person lives, and it ends when that person dies. That much is simple. What is not simple is the final period. If someone entitled to annual income dies part-way through a year, has the payer's obligation for that year vanished, accrued in full, or accrued only up to the day of death? The answer is worth money, and it turns entirely on how the annuity was structured to be paid. Article 2025 settles it with a default rule and one important exception, so the arithmetic does not depend on argument.
The default: pay in proportion to days lived
The default is a day-by-day apportionment. The income corresponding to the year in which the person enjoying it dies shall be paid in proportion to the days during which he lived. So where the income accrues over the period and is not prepaid, the estate is owed only the fraction earned before death: count the days the person lived in that final year and pay that proportion of the year's income. Nothing is owed for the days after death, because the annuity was consideration for the person's continued life and that consideration stopped when he died. This is the ordinary case, and it produces a clean pro-rata figure.
The exception: advance instalments are paid in full
The exception reverses that where payment was front-loaded. If the income should be paid by installments in advance, the whole amount of the installment which began to run during his life shall be paid. When an instalment is payable at the start of its period, it falls due the moment that period begins. If the annuitant was alive on the day the instalment began to run, the entire instalment is earned and owed, even if he dies the next day and most of the period goes unspent. There is no clawback of the unused portion, because the whole instalment had already become payable while he lived.
Which rule applies to you
So the single question that decides the amount is how the annuity was payable. If income accrued over each period and was collected in arrears, apportion it to the days lived in the final year and pay that share to the estate. If instalments were payable in advance, identify the instalment that had begun to run when the person died and pay it in full, with no apportionment. The annuity contract is where this is written — the frequency of payment and whether it fell due at the beginning or the end of each period — so that document, read against the date of death, gives the figure directly.