In the Philippines, the dissolution of a "live-in" relationship (legally termed as a union without marriage) often brings to the surface unresolved financial obligations. Whether the money in question was a personal loan, a shared investment, or a contribution to household expenses, the legal remedy for recovery depends heavily on the nature of the relationship and the evidence of the debt.

1. Determining the Legal Regime of the Union

Before filing a collection case, one must identify which provision of the Family Code of the Philippines governs the property relations of the partners. This determines whether the money is considered "common property" or a personal debt.

Article 147: Parties Capacitated to Marry

This applies to a man and a woman who live together as husband and wife but are not married, provided they have no legal impediment to marry (e.g., both are single, widowed, or their previous marriages were annulled).

Ownership: Salaries and wages earned by either party belong to them in equal shares.
Presumption: Property acquired during the cohabitation is presumed to be owned in common.
Collection Implication: If a partner "borrowed" from the other’s salary, the creditor-partner may only be able to collect the portion that exceeds the debtor-partner's 50% share, unless it was clearly a loan of separate property owned before the union.

Article 148: Parties with Legal Impediments

This applies to cohabitation where one or both parties are incapacitated to marry (e.g., one partner is still legally married to someone else/adulterous relationships).

Ownership: Only properties acquired through actual joint contribution of money, goods, or industry are owned in common.
Presumption: There is no automatic 50/50 split. The share is in proportion to the actual contribution.
Collection Implication: If a partner cannot prove actual contribution, they cannot claim ownership. A collection of a sum of money is more straightforward here if the money can be proven to be a personal loan unrelated to joint acquisitions.

2. The Nature of the Action: Collection of Sum of Money

A "Collection of Sum of Money" is a civil action filed to compel a debtor to pay a certain amount of money arising from law, contracts, quasi-contracts, or quasi-delicts.

The Demand Letter

Under Philippine law, a debtor is generally not in "legal delay" until a demand is made. Before filing a case in court, the creditor-partner must send a formal Demand Letter via registered mail. This letter serves as evidence that the partner was given the opportunity to pay and failed to do so.

Small Claims Cases

If the amount being claimed does not exceed PHP 1,000,000.00 (exclusive of interests and costs), the case falls under the Revised Rules on Summary Procedure and Rituals for Small Claims Cases.

No Lawyers: Lawyers are not allowed to represent parties in the hearing.
Speed: These cases are designed to be resolved quickly, often in a single hearing.
Process: Filing a verified Statement of Claim with attached evidence (promissory notes, receipts, etc.).

Ordinary Civil Actions

If the claim exceeds PHP 1,000,000.00, the case is filed as an ordinary civil action in the Regional Trial Court (RTC). This process is more formal, requires legal counsel, and involves a full-blown trial.

3. Necessary Evidence

In civil cases, the burden of proof is preponderance of evidence—meaning the evidence must be more convincing than that of the opposing party. Key evidence includes:

Promissory Notes: Any written document signed by the partner acknowledging the debt.
Bank Transfers/Mobile Wallet Receipts: Proof of the actual transfer of funds (e.g., GCash, PayMaya, or bank deposit slips).
Digital Correspondence: Messages on SMS, Viber, or Messenger can be admitted as electronic evidence under the Rules on Electronic Evidence, provided they can be authenticated.
Testimonial Evidence: Statements from witnesses who were present when the loan was negotiated or given.

4. Possible Defenses

The defendant-partner may raise several defenses to avoid payment:

Donation/Gift: The partner may claim the money was a gift (liberality) given during the relationship, which does not require repayment.
Contribution to Household Expenses: The partner may argue the money was their share for rent, utilities, or food, rather than a loan.
Prescription: Under the Civil Code, actions based on a written contract must be brought within 10 years, while oral contracts must be brought within 6 years.

5. The Barangay Conciliation Requirement

Since live-in partners usually reside in the same household or barangay, the case must generally go through Barangay Conciliation (Katarungang Pambarangay) before reaching the courts.

A Certificate to File Action is required from the Lupon Tagapamayapa.
Failure to undergo this process can lead to the dismissal of the court case for "lack of cause of action" or "prematurity."

6. Provisional Remedies: Preliminary Attachment

In cases where the creditor-partner fears that the other partner might hide or dispose of their assets (e.g., selling a car or leaving the country) to avoid payment, they may pray for a Writ of Preliminary Attachment. If granted, the court can "attach" or freeze the debtor-partner’s properties as security for the satisfaction of any judgment.