In Philippine remedial law, a Final Demand Letter is often the "point of no return." It serves as the formal act of putting the obligor in default (mora solvendi). Under Article 1169 of the Civil Code, those obliged to deliver or to do something incur in delay from the time the obligee judicially or extrajudicially demands from them the fulfillment of their obligation.

Once the period specified in that final demand letter (e.g., 5, 7, or 15 days) has lapsed without compliance, the right of action accrues. Here is the comprehensive roadmap of the next legal steps within the Philippine jurisdiction.

1. Verification of Proof of Service

Before filing any case, you must ensure you can prove the demand was actually received. In Philippine courts, a "demand" that cannot be proven is legally non-existent.

Personal Service: Ensure you have a copy of the letter with the receiving party’s printed name, signature, and date.
Registered Mail: Secure the Registry Receipt and, more importantly, the Registry Return Card from the Post Office.
Courier (LBC/J&T/Grab): Print the tracking web page showing "Delivered" and, if possible, get an affidavit from the sender or a certification from the courier.

2. Mandatory Conciliation Proceedings

In the Philippines, you generally cannot go straight to court if the parties reside in the same city or municipality.

Katarungang Pambarangay (Barangay Conciliation): Under the Local Government Code, most civil disputes (and some criminal cases) must undergo mediation before the Lupon Tagapamayapa.
The Goal: To obtain a Certificate to File Action. Without this certificate, the court may dismiss your complaint for "failure to comply with a condition precedent."
Exceptions: Barangay conciliation is not required if:
One party is a corporation or a juridical entity.
The parties reside in different cities or municipalities (not adjoining).
The dispute involves real property located in a different city.
Urgent cases involving petitions for habeas corpus or preliminary injunctions.

3. Determining the Proper Venue and Jurisdiction

You must decide which court has the authority to hear your case. This is determined by the nature of the claim and the amount involved (exclusive of interests, damages, and attorney's fees).

Small Claims Cases: For purely money claims (e.g., unpaid loans, rent, liquidated damages) not exceeding P1,000,000.00. These are summary in nature; no lawyers are allowed to represent parties during the hearing, and the process is expedited.
Civil Actions (Sum of Money/Specific Performance):
Metropolitan/Municipal Trial Courts (MeTC/MTCC/MTC): If the claim exceeds P1,000,000.00 but falls within the jurisdictional limits set by the Judiciary Reorganization Act as amended by R.A. 11576.
Regional Trial Courts (RTC): Generally for claims exceeding P2,000,000.00 (in certain areas) or cases where the subject matter is "incapable of pecuniary estimation" (e.g., Rescission of Contract).

4. Filing the Complaint and Provisional Remedies

Once the demand has lapsed and conciliation has failed, your lawyer will draft the Verified Complaint.

Certification Against Forum Shopping: You must swear that you haven't filed the same case elsewhere.
Provisional Remedies: If you fear the debtor will hide their assets while the case is ongoing, you may pray for a Preliminary Attachment under Rule 57. This allows the court to "attach" or freeze the defendant’s properties as security for the satisfaction of any judgment.

5. Special Considerations for Specific Cases

The "next step" varies significantly based on the underlying cause of action:

For Unpaid Checks (B.P. 22): The lapse of the 5-day period after a notice of dishonor creates a prima facie presumption of knowledge of insufficiency of funds. You may then file a criminal complaint for violation of the Bouncing Checks Law.
For Ejectment (Unlawful Detainer): If the demand was to vacate the premises, the lapse of the period gives you one year to file an Unlawful Detainer case in the MTC. This is a summary procedure.
For Foreclosure: If the debt is secured by a mortgage, the lapse of the demand allows the creditor to initiate Extrajudicial Foreclosure under Act 3135 (via the Sheriff/Notary Public) or Judicial Foreclosure under Rule 68.

6. The "Demand" as a Trigger for Interest

Legally, the lapse of the demand letter marks the start of Legal Interest. Per Nacar vs. Gallery Frames, the current legal interest rate in the Philippines is 6% per annum from the time of extrajudicial or judicial demand. By documenting the lapse of the letter, you are effectively increasing the amount of the final judgment every day the debtor refuses to pay.

Summary Checklist

Consolidate Evidence: Receipts, contracts, and the Return Card.
Barangay Mediation: Secure the Certificate to File Action if applicable.
Choose the Forum: Small Claims (up to P1M) or regular Civil Suit.
Draft the Complaint: Include a prayer for damages and attorney's fees.
Pay Filing Fees: The court will not take jurisdiction until the "docket fees" are paid.