The Quezon City Government uses Geographic Information Systems to infuse greater efficiency and accuracy in the work of the City Assessor's Office (CAO). A geographic information system (GIS) is a computer system designed to capture, store, manipulate, analyze, manage, and present all types of spatial or geographical data.
The use of this technology is under the CAO's Enhanced Tax Mapping Systems Project which has established the synchronized updating of tax maps and tax declaration records. The application of GIS for tax mapping has enabled the CAO to trim down duplications in property index number (PIN) assignments, double assessments due to overlapping claims, and similar issues, to arrive at more accurate property records.
GIS has also made possible easy identification and resolution of problem areas when comparing tax maps, existing assessment records and accounting of all parcels. The resulting data cleansing and revalidation has resulted in approximately 153% increase in estimated tax due from real property taxes. Among the problems detected and assessed for further inspection and updating/ correction are the following: