Filing a complaint against online scammers in the Philippines requires a systematic approach, leveraging specific laws designed to combat cybercrime and protect consumers. Under the Cybercrime Prevention Act of 2012 (Republic Act No. 10175) and the Consumer Act of the Philippines (Republic Act No. 7394), victims have several legal avenues for redress.

1. Immediate Preparatory Steps

Before approaching authorities, documentation is the most critical component of a successful complaint. Evidence must be preserved in its original digital format where possible.

Screenshots: Capture the scammer’s profile, URLs, exchange of messages, and the specific advertisement or post.
Transaction Records: Save receipts, deposit slips, mobile wallet (GCash/Maya) confirmation screenshots, and bank statements.
Digital Footprint: Note the date, time, and platform (e.g., Facebook Marketplace, Telegram) where the transaction occurred.

2. Where to File: Key Government Agencies

A. PNP Anti-Cybercrime Group (PNP-ACG)

The PNP-ACG is the primary unit for investigating online fraud.

Process: Victims should visit the nearest ACG District Office or the headquarters at Camp Crame.
Action: They will conduct a technical evaluation of the evidence and can assist in tracking the digital identity of the perpetrator.

B. NBI Cybercrime Division (NBI-CCD)

The National Bureau of Investigation handles complex cybercrime cases and provides a formal platform for filing complaints.

Online Portal: Complaints can be initiated through the NBI’s official website or via email.
Walk-in: You may file a formal affidavit of complaint at the NBI Cybercrime Division in Manila or regional offices.

C. Department of Trade and Industry (DTI)

If the "scam" involves a registered business failing to deliver goods or providing deceptive descriptions, the DTI handles the mediation.

Focus: Violations of the Consumer Act (e.g., deceptive sales acts).
Constraint: The DTI generally handles administrative cases against legitimate businesses rather than unidentified criminal individuals.

3. Legal Framework and Penalties

The primary law invoked is RA 10175 (Cybercrime Prevention Act). Common charges include:

Computer-related Fraud: Unauthorized input, alteration, or deletion of computer data with the intent of procuring an economic benefit.
Identity Theft: The intentional acquisition or use of identifying information belonging to another person.
Estafa under the Revised Penal Code: When deceit and damage (financial loss) are present, "Cyber-Estafa" carries higher penalties than traditional Estafa—specifically, a penalty one degree higher than that prescribed by the Revised Penal Code.

4. The Formal Procedure for Prosecution

Affidavit of Complaint: You must execute a sworn statement detailing how the scam occurred. This is usually done with the assistance of the PNP or NBI.
Preliminary Investigation: The complaint is forwarded to the Office of the Prosecutor. The prosecutor determines if there is "probable cause" to bring the case to court.
Filing in Court: If probable cause is found, an "Information" (criminal charge) is filed in the Regional Trial Court (RTC) designated as a Cybercrime Court.
Issuance of Warrant: The court will issue a warrant of arrest for the identified suspect.

5. Important Considerations

Small Claims Court: If the scammer’s identity is known and the primary goal is recovering a sum of money (not exceeding ₱1,000,000), a civil case for Small Claims can be filed. This process does not require a lawyer.
Prescription Period: Under RA 10175, the state has up to 15 years to file a criminal action, but immediate filing is recommended to prevent the disappearance of digital evidence.
Bank/Wallet Reporting: Simultaneously notify the involved financial institution (e.g., the bank or GCash). While they cannot reverse transactions without a court order or the recipient's consent, they can freeze accounts flagged for suspicious activity during an investigation.