Short answer. Yes, presumptively. Article 1602 of the Civil Code presumes a contract with a right to repurchase is really an equitable mortgage when the purchaser retains for himself a part of the purchase price. This presumption can be overcome, but on its own it points toward a mortgage rather than a true sale.
What the law says
The contract shall be presumed to be an equitable mortgage, in any of the following cases
Civil Code, Article 1602 — When a Sale Is Really a Mortgage. Read the full provision →
What the law says
When the purchaser retains for himself a part of the purchase price
Civil Code, Article 1602 — When a Sale Is Really a Mortgage. Read the full provision →
Why this circumstance points to a mortgage
Article 1602 lists several situations in which a sale with a right to repurchase is presumed to actually be an equitable mortgage rather than a genuine sale. One of them is when the purchaser retains for himself a part of the purchase price. The reasoning is that a real buyer ordinarily pays the full agreed price to acquire the property; a buyer who instead keeps back part of it looks more like a lender holding back an amount connected to the debt the transaction is actually meant to secure.
What presumed means here
Because Article 1602 creates a presumption rather than an absolute rule, the fact that the buyer retained part of the price does not by itself conclusively prove the transaction is a mortgage; it shifts the analysis in that direction and puts the burden on whoever insists it was a genuine sale to show otherwise. Other circumstances in the same transaction, and the parties' actual conduct afterward, can support or undermine that presumption alongside this one factor.
What follows if the presumption applies
If the contract is treated as an equitable mortgage rather than a true sale, Article 1602 also affects how anything the buyer received as rent or otherwise is characterized: any money, fruits, or other benefit received by the buyer is treated as interest, subject to the laws on usury, rather than as the fruits of ownership. The buyer is functionally treated as a lender under this presumption, and the seller retains rights closer to those of a borrower than someone who has permanently parted with the property.
Other circumstances that can reinforce or weaken this
Article 1602 lists several other situations alongside the retained purchase price, such as an unusually inadequate price, the seller staying in possession, or the seller continuing to pay taxes on the property. If more than one of these circumstances is present in your transaction, that generally strengthens the case that it is an equitable mortgage; if the retained price is the only unusual feature and everything else about the deal looks like an ordinary sale, the presumption may be more open to being rebutted with contrary evidence.