Short answer. The value of your interest at dissolution. Under Article 1841, when a partner retires and the business is continued without a settlement of accounts, he may have the value of his interest at the date of dissolution ascertained and, as an ordinary creditor, receive an amount equal to that value, with interest.
What the law says
shall receive as an ordinary creditor an amount equal to the value of his interest in the dissolved partnership with interest
Civil Code, Article 1841 — Retiring/Deceased Partner's Interest When Business Continues. Read the full provision →
You are owed the value of your interest
When a partner leaves — by retirement or death — but the remaining partners carry the business on rather than winding it up and settling accounts, Article 1841 protects the departing partner's stake. He, or his legal representative, may have the value of his interest at the date of dissolution ascertained, and shall receive as an ordinary creditor an amount equal to the value of his interest in the dissolved partnership with interest. Two things stand out. The value is fixed as at the date of dissolution — the moment he ceased to be a partner — not at some later or earlier point.
Interest or a share of profits — your choice
The article gives the departing partner a choice about what he gets on top of the value of his interest. He may take that value with interest — a return for being kept out of his money while the business used it. Or, at his option, in lieu of interest, he may take the profits attributable to the use of his right in the property of the dissolved partnership. This second option matters when the continuing business did well: rather than a fixed interest rate, the retiring partner can claim the share of the profits that his capital, left in the business, helped to generate.
But the firm's creditors come first
There is an important qualification on this claim. Although the retiring partner ranks as a creditor of the continuing business, the article makes the creditors of the dissolved partnership rank ahead of him. Their claims have priority over any claim the retired or deceased partner brings under this article. This makes sense: the firm's outside debts, incurred while he was a partner, should be met before he draws out the value of his stake. So the retiring partner is a creditor, but not a first-priority one — he stands behind the partnership's own creditors.
If you are retiring and the firm continues
If you are stepping out while the others carry on, the first thing to establish is the value of your interest as at the date you leave, because that figure — properly ascertained from the accounts — is the measure of what you are owed. Decide, or reserve, whether you will take interest on that value or the profits attributable to the use of your share, and watch how the business performs, since that can determine which is worth more. And understand your standing: you are a creditor of the continuing firm, but one who ranks behind its outside creditors.