Short answer. Yes. Under the Civil Code rule on partnership by estoppel, a person who represents himself as a partner, or who consents to being presented as one, answers to anyone who extended credit on the strength of that representation — even though he never contributed capital and never signed a partnership agreement.
What the law says
When a person, by words spoken or written or by conduct, represents himself, or consents to another representing him to anyone, as a partner in an existing partnership or with one or more persons not actual partners, he is liable to any such persons to whom such representation has been made, who has, on the faith of such representation, given credit to the actual or apparent partnership
Civil Code, Article 1825 — Partnership by Estoppel. Read the full provision →
Liability comes from the appearance, not the paperwork
Article 1825 does not ask whether a partnership exists. It asks what the creditor was led to believe. The representation can be made by words spoken or written or by conduct — so a name on a signboard or a calling card, an introduction at a meeting you did not correct, or letting your photograph and title sit on a company brochure can be enough. What converts appearance into liability is reliance: the creditor must have on the faith of such representation, given credit to the actual or apparent partnership. A supplier who was never told about you, or who dealt with the business for its own reasons, has no claim under this article.
Consent counts as much as speaking
The most common trap is passive. The article catches a person who consents to another representing him as a partner. If a friend uses your name to reassure lenders and you know about it and say nothing, the law treats your silence as participation. It goes further where the representation was made in a public manner: then you can be liable to a creditor even if that particular creditor never heard it from you and the apparent partner did not know he was passing it on. That is why a written demand that your name be removed from signage, listings and marketing material — kept and dated — matters so much.
How much you owe depends on who else consented
The article sets two levels. When a partnership liability results, he is liable as though he were an actual member of the partnership — that is the harshest outcome, reached where all the real partners consented to the representation, because the obligation is then the partnership's own. When no partnership liability results, he is liable pro rata with the other persons, if any, so consenting, and separately where there is nobody else. A further consequence is easy to miss: the person held out as a partner becomes an agent of those who consented, able to bind them to persons who rely on the representation.
What this does not do
Being liable by estoppel does not make you a partner. You gain no share in profits, no right to manage, no interest in partnership property, and no claim to a share on dissolution — the article creates a one-way exposure to outsiders who relied on the appearance. It also does not reach creditors who knew the truth, or persons whose loss has nothing to do with credit given on the faith of the representation. If a demand letter or a collection suit has arrived naming you as a partner, gather every document showing what you did and did not hold out — and take advice quickly, because deadlines to answer a complaint are short.