Philippine Standard Geographic Code (PSGC) Guide

PSGC Code Structure: 9-Digit Legacy vs 10-Digit Standard

Spatial datasets in the Philippines currently use two primary numeric lengths. The PSA introduced the 10-digit standard in 2018 to resolve digit exhaustion in rapidly subdividing municipalities. Developers must support both structures when ingesting spatial archives.

Philippine Administrative Levels Under Republic Act No. 7160

The local governance hierarchy follows the Local Government Code of 1991 (Republic Act No. 7160). Each level holds defined political powers, taxation authorities, and statutory responsibilities:

Critical Boundary Cases: NIR, BARMM SGA, and Supreme Court Rulings

GIS pipelines frequently break when using outdated reference tables. Developers must account for three significant administrative boundary updates:

Database Schema Design: Storing and Indexing PSGC in PostgreSQL

A frequent database anti-pattern is storing PSGC codes as numeric integers (INT or BIGINT). Because Northern Luzon regions use leading zeros (e.g., Ilocos Region is 01, Cagayan Valley is 02, Central Luzon is 03), integer types automatically strip the zero. This turns 037114000 into 37114000, breaking 9-character fixed-length string joins.

Always store PSGC codes as fixed-length or variable-length text fields with B-Tree indexes on administrative substring slices:

-- PostgreSQL / PostGIS Schema for PSGC Administrative Boundaries
CREATE TABLE ph_administrative_boundaries (
    id SERIAL PRIMARY KEY,
    psgc_code VARCHAR(10) NOT NULL UNIQUE,
    name VARCHAR(255) NOT NULL,
    admin_level VARCHAR(20) NOT NULL CHECK (admin_level IN ('region', 'province', 'city', 'municipality', 'barangay')),
    region_code VARCHAR(2) GENERATED ALWAYS AS (SUBSTRING(psgc_code FROM 1 FOR 2)) STORED,
    province_code VARCHAR(4) GENERATED ALWAYS AS (SUBSTRING(psgc_code FROM 1 FOR 4)) STORED,
    geom GEOMETRY(MultiPolygon, 4326) NOT NULL
);

-- Fast B-Tree indexing on administrative slices
CREATE INDEX idx_admin_region ON ph_administrative_boundaries (region_code);
CREATE INDEX idx_admin_province ON ph_administrative_boundaries (province_code);
CREATE INDEX idx_admin_level ON ph_administrative_boundaries (admin_level);

-- Spatial index for point-in-polygon coordinates lookup
CREATE INDEX idx_admin_geom ON ph_administrative_boundaries USING GIST (geom);

-- Example: Find the exact LGU for a WGS84 GPS coordinate (e.g. Subic, Zambales)
SELECT psgc_code, name, admin_level
FROM ph_administrative_boundaries
WHERE ST_Contains(geom, ST_SetSRID(ST_Point(120.2315, 14.8803), 4326))
ORDER BY admin_level DESC;

TypeScript Utility: Parsing 9-Digit and 10-Digit PSGC Codes

The utility below handles both legacy 9-digit and modern 10-digit formats, validates numeric format, and returns the structural hierarchy slices:

export interface PsgcEntity {
  rawCode: string;
  codeLength: 9 | 10;
  regionPrefix: string;
  provincePrefix: string;
  cityMuniPrefix: string;
  barangayPrefix: string;
  isBarangay: boolean;
  isValid: boolean;
}

/**
 * Parses and validates a raw PSGC string into geographic hierarchy prefixes.
 * Handles both 9-digit (legacy) and 10-digit (expanded) formats.
 */
export function parsePsgc(input: string | number): PsgcEntity {
  const raw = String(input).trim();
  const digitsOnly = raw.replace(/\D/g, '');
  const isValidLength = digitsOnly.length === 9 || digitsOnly.length === 10;

  if (!isValidLength) {
    return {
      rawCode: raw,
      codeLength: 9,
      regionPrefix: '',
      provincePrefix: '',
      cityMuniPrefix: '',
      barangayPrefix: '',
      isBarangay: false,
      isValid: false
    };
  }

  const length = digitsOnly.length as 9 | 10;
  const regionPrefix = digitsOnly.slice(0, 2);

  // In 9-digit codes: Province is 2 digits (pos 2-4), City is 2 digits (pos 4-6), Brgy is 3 digits
  // In 10-digit codes: Province is 3 digits (pos 2-5), City is 2 digits (pos 5-7), Brgy is 3 digits
  const provincePrefix = length === 9 ? digitsOnly.slice(0, 4) : digitsOnly.slice(0, 5);
  const cityMuniPrefix = length === 9 ? digitsOnly.slice(0, 6) : digitsOnly.slice(0, 7);
  const barangaySuffix = length === 9 ? digitsOnly.slice(6, 9) : digitsOnly.slice(7, 10);
  const isBarangay = barangaySuffix !== '000';

  return {
    rawCode: digitsOnly,
    codeLength: length,
    regionPrefix,
    provincePrefix,
    cityMuniPrefix,
    barangayPrefix: isBarangay ? digitsOnly : '',
    isBarangay,
    isValid: true
  };
}

// Example usage:
const subic = parsePsgc('037114000');
console.log(subic.regionPrefix);   // '03' (Central Luzon)
console.log(subic.provincePrefix); // '0371' (Zambales)
console.log(subic.isBarangay);     // false (Municipal level)