Short answer. The partnership bears that loss, not the contributing partner. Under Article 1787 of the Civil Code, once goods a partner contributes are appraised and brought in, any subsequent change in their value, up or down, is for the account of the partnership. The partner is credited with the appraised value.
What the law says
When the capital or a part thereof which a partner is bound to contribute consists of goods, their appraisal must be made in the manner prescribed in the contract of partnership, and in the absence of stipulation, it shall be made by experts chosen by the partners, and according to current prices, the subsequent changes thereof being for account of the partnership.
Civil Code, Article 1787 — Appraisal of Contributed Goods. Read the full provision →
The partnership absorbs the change
When a partner's contribution takes the form of goods, the value of those goods can move after they are brought in, and someone must bear that movement. Article 1787 of the Civil Code answers that it is the partnership. After the goods are appraised, the article says they are valued according to current prices, the subsequent changes thereof being for account of the partnership. In plain terms, once the goods are appraised and contributed, any later rise or fall in their market value belongs to the firm, not to the partner who brought them. If they drop in value afterward, that decline is the partnership's loss, not the contributor's.
Why the appraisal locks in your credit
The reason is that the appraisal fixes, once and for all, what the contributing partner is credited with. The value set at the time of contribution becomes his capital contribution, and it does not shrink or grow with the market afterward. So a partner who contributed goods worth a certain amount on the day they were appraised keeps that credit even if the goods later lose value. The flip side is that he also does not gain if they later become more valuable; that upside likewise goes to the partnership. The appraisal draws a clean line between the partner's fixed credit and the firm's fluctuating fortunes.
How the goods are appraised
The article is also specific about how the valuation is done, which matters because that figure is decisive. It says the appraisal must be made in the manner prescribed in the contract of partnership, and in the absence of stipulation, it shall be made by experts chosen by the partners, and according to current prices. So the partners' own agreement controls first; if they set a method in the contract, that governs. Only when the contract is silent does the law supply a default: valuation by experts the partners choose, based on current prices. Either way, the goal is an objective, agreed value rather than one side's say-so.
What this means in practice
For a partner contributing goods, the practical takeaways are clear. Insist on a proper appraisal, because that value becomes your fixed credit in the firm regardless of what happens to prices later. Once the goods are in, you are protected from a later drop in their value, but you also give up any later gain. Because the appraisal figure carries such weight, it is worth agreeing on the method, whether by a clause in the partnership contract or by experts, before the goods change hands. A careless valuation can shortchange the contributor or unfairly burden the firm.