In the Philippines, a name is not merely a label; it is a matter of public interest and a civil registry record. Consequently, changing one's surname is not a simple choice but a formal legal process governed by specific laws and jurisprudence. Under Philippine law, there are two primary pathways for changing a surname: Administrative Correction (under Republic Act No. 9048, as amended) and Judicial Petition (under Rule 103 of the Rules of Court).

I. The General Rule of Immutability

The prevailing principle in Philippine law is that a person cannot arbitrarily change their name. The State has an interest in maintaining the identity of its citizens to prevent confusion, fraud, or the evasion of obligations. However, the law provides specific grounds where a change is justified to avoid prejudice or to reflect a change in civil status.

II. Administrative Change (R.A. 9048 as amended by R.A. 10172)

This is the "summary" or faster route. It does not require a court appearance and is handled by the Local Civil Registrar (LCR) where the birth record is kept.

1. Grounds for Administrative Change

You can use this route only if the reason for the change is to:

Correct a clerical or typographical error (e.g., "Gonzales" to "Gonzalez").
Change a first name or nickname that is ridiculous, tainted with dishonor, or extremely difficult to write or pronounce.
Update a name where the new name has been habitually and continuously used by the petitioner and they are publicly known by that name.

2. The Process

Filing: File a verified petition with the LCR of the city or municipality where the birth was registered. If living abroad, file with the nearest Philippine Consulate.
Publication: The petition must be published once a week for two consecutive weeks in a newspaper of general circulation.
Posting: The notice is posted in a public place for ten days.
Decision: The LCR reviews the evidence and issues a decision. This decision is then subject to affirmation by the Civil Registrar General (National Statistician).

III. Judicial Change of Name (Rule 103)

If the change you seek is "substantial" and goes beyond a simple typo—such as changing your surname to your mother's name or changing it entirely—you must file a Petition for Change of Name in the Regional Trial Court (RTC).

1. Valid Grounds for Judicial Change

The Supreme Court has recognized several grounds for a judicial change of name:

When the name is ridiculous, tainted with dishonor, or extremely difficult to write or pronounce.
When the change is a result of a change in civil status (e.g., legitimation).
When the change is necessary to avoid confusion.
When a person has continuously used and been known by a different surname since childhood.
When a surname is changed to avoid the stigma of illegitimacy.

2. The Judicial Process

Petition: File a verified petition in the RTC of the province where the petitioner has resided for at least three years.
Order of Hearing: The court issues an order setting the case for hearing.
Publication: The order must be published once a week for three consecutive weeks in a newspaper of general circulation.
Hearing: The petitioner must prove the grounds in court. The Office of the Solicitor General (OSG), representing the State, may oppose the petition.
Judgment: If granted, the court issues a decree, which must be registered with the LCR and the Philippine Statistics Authority (PSA).

IV. Specific Scenarios for Surnames

1. Illegitimate Children

Under Republic Act No. 9255, illegitimate children may use the surname of their father if the father has formally recognized the child through an Affidavit of Admission of Paternity or a Private Handwritten Instrument. If the child was originally registered under the mother’s surname, an administrative process (not a court case) is usually sufficient to update the record once paternity is acknowledged.

2. Married Women

Under the Civil Code (Art. 370), a married woman has the option but not the obligation to use her husband's surname. She may:

Use her maiden first name and surname and add her husband’s surname.
Use her maiden first name and her husband’s surname.
Use her husband’s full name, but prefixing a word indicating that she is his wife, such as “Mrs.”

Once a woman chooses to use her husband's surname in her passport or civil records, she cannot revert to her maiden name unless the marriage is legally dissolved (Annulment, Nullity, or Divorce for foreigners/Muslims) or she is widowed.

V. Essential Requirements

Regardless of the route, you will generally need the following documents:

PSA Birth Certificate (the copy containing the error or the name to be changed).
Clearances: NBI, Police, and Court clearances to prove you are not changing your name to hide a criminal record.
Proof of Use: School records (Form 137), Employment records, or Baptismal certificates showing the name you wish to adopt.
Affidavits: From disinterested persons who can vouch for your identity.

VI. Summary of Differences

Feature	Administrative (RA 9048/10172)	Judicial (Rule 103)
Where to file	Local Civil Registrar	Regional Trial Court
Nature of Error	Clerical/Typographical	Substantial/Fundamental
Cost	Lower (Filing fees + Publication)	Higher (Legal fees + Publication)
Timeframe	Usually 3 to 6 months	Usually 1 to 2 years
Final Approval	Civil Registrar General	Court Judgment