The National Statistics Office (formerly National Census and Statistics Office from 1974 up to it's renaming by virtue of Executive Order 121 on January 30, 1987 and used to be the Bureau of the Census and Statistics prior to its re-organization under PD 418 on March 20, 1974) became the sole agency to compile foreign trade statistics starting in 1973.

Prior to this period, the Central Bank of the Philippines (now known as Bangko Sentral ng Pilipinas) also compiled and released foreign trade data. However, the differences in the concepts used by these two agencies resulted to a conflicting foreign trade data. This led to an agreement that sets NSO to be the sole compiler of the official foreign trade statistics.

The Philippines adopts the "General" trade system of recording foreign trade statistics. The customs frontier (not the national boundary) is used as the statistical frontier. Under this system, all goods entering any of the seaports or airports of entry of the Philippines properly cleared through customs or remaining or under customs control are considered imports, whether the goods are for direct consumption, for merchandising, for warehousing or further processing. On the other hand, all goods leaving the country, which are properly cleared through the Customs, are considered exports. A distinction however, is made between export for goods grown, mined or manufactured in the Philippines (domestic exports) and exports of imported goods that do not undergo physical and/or chemical transformation in the Philippines (re-exports).

The foreign trade data contained in this report relates to commerce between the Philippines and other countries by sea or air whether for private or government use or for commercial purposes, gifts or samples. It also includes animals for the zoo, for breeding and the like. However, the following classes of goods are excluded in the compiled foreign trade statistics:

• Fish and other marine products landed by Philippine vessel direct from the sea;
• Goods imported and exported by, or on behalf of diplomatic services and armed forces;
• Exposed cinematographic films imported or exported on rental basis;
• Personal effects of passenger on which no duty was paid;
• Issued currency notes and coins;
• Goods in transit to foreign countries;
• Stores and fuels purchased abroad by ships and aircrafts of Philippine registry; and
• Goods sent through parcel posts.

Since 1982, goods are considered imported/exported on the date the carrying vessel/aircraft arrives/departs at the port/airport of unloading/loading.

The coverage of the annual publication is usually higher than the sum of monthly coverage, since it includes data from the documents, which arrived late for inclusion in their respective months. Monthly figures in this publication, however, include these corrections.

Foreign trade statistics are compiled by the National Statistics Office (NSO) from copies of import and export documents submitted by importers and exporters or their authorized representatives to the Bureau of Customs (BOC) as required by law. Imported articles of commercial nature with dutiable value of two thousand pesos and above are cleared on formal import entry (BOC Import Entry and Internal Revenue Declaration-Form No. 236). Those with dutiable value of two thousand pesos or less and personal and household effects, are cleared on an informal import entry (Informal Import Declaration and Entry - BC Form No. 177) whenever duty, tax or charges are collectible.

Effective 1980, EPZA Import Tally (Form No. 8102) are used for clearing importations intended for Export Processing Zones. However, the Customs-EPZA Warehousing Entry (BC Form No. 242 - CEWE) which was implemented in 14 October 1991 revoked the use of the EPZA Import Tally. However, from early 1996 to the present, EPZA forms were renamed as PEZA (Philippine Economic Zone Authority) forms after the name of the agency.

Another source of import data used for clearance of cargoes is the Single Administrative Document (SAD), an electronic copy of the IEIRD. This is an on-line submission of import documents either by brokers or companies in lieu of the manual filling-up of documents.

The sources of export data, on the other hand, are Export Permit (CB-ED Form No. 102R), Export Declaration (ED) with and without Foreign Exchange Proceeds (CBP 6-21-02 and CBP 6-21-04, respectively) and PEZA Export Tally (PEZA Form No. 8104). The first form is used by Board of Investments (BOI) - registered exporters, the second form by general exporters and the last form by exporters located inside the Export Processing Zones. Effective 1 October 1991, the Revised Export Declaration was implemented which can be used by all kinds of exporters including general, BOI registered and PEZA registered exporters. Starting 30 July 1996, this form was then implemented under the Department of Trade and Industry (DTI) from the Central Bank (CB) of the Philippines.

Other sources of export data are the General System of Preferences (GSP Form A), ASEAN Common Effective Preferential Tariff Scheme (Form D) and ASEAN-CHINA Free Trade Area Preferential Tariff (Form E). These documents are issued by the Bureau of Customs to exporters whose products are eligible for preferential tariff treatment.

Monthly reports of selected electronic companies were also used as sources of export data. In addition, the Special Permit to Load (SPL) was used for those selected companies without corresponding export document.

Starting in 2003, the Automated Export Documentation System (AEDS), a paperless recording of export transaction at the ECOZONES covering semiconductor and electronic shipments loaded at Ninoy Aquino International Airport (NAIA) was included in the compilation of export statistics. This is due to the Joint Memorandum Order (JMO) No. 02-2002 section 3.9, which states that "in lieu of providing the NSO and DTI copies (paper) of the ED, the BOC shall provide electronic files of ED's processed on a monthly basis to these government agencies". The NSO collects this electronic files every 15th day of the month and integrates them to the NSO database system.

In addition to NAIA, all transactions that pass through AEDS in Subic and Mactan were also included in the compilation of export statistics starting in 2004 and 2005, respectively.

Revision in the import figures were done for the years 2000 to 2004. The revision on import statistics was based on the recommendation of the Inter-Agency Committee on Trade. The committee is composed of representatives from the National Statistical Coordination Board (NSCB), Bangko Sentral ng Pilipinas (BSP), National Economic Development Authority (NEDA), NSO, PEZA, BOC and DTI-Export Development Council (EDC) and Bureau of Export Trade Promotion (BETP). The NSCB Executive Board approved the recommended methodology last May 8, 2005 through NSCB Resolution No. 8 Series of 2005 entitled "Interim Methodology for the Revision of Electronics Import Statistics". However, starting in 2006, import figures were adjusted based on the transactions that pass through the Automated Cargo Operating System (ACOS) of the Bureau of Customs (BOC).

The commodities are classified in accordance with the 1993 Philippine Standard Commodity Classification Revised 2 (1993 PSCC Rev. 2), a classification scheme that is aligned with the United Nations Standard International Trade Classification (SITC),  and the Harmonized Commodity Description and Coding System of the Philippines, otherwise known as Harmonized System of the Philippines (HSP)  from 1999 to 2006. However, starting with July 2006, all commodities are both classified in accordance with the 1993 Philippine Standard Commodity Classification Revised 2 (1993 PSCC Rev. 2)  and with the 2004 Philippine Standard Commodity Classification (2004 PSCC)  groupings. This is in compliance with NSCB Resolution No. 03, Series of 2005 entitled "Approving and Adopting the 2004 Philippine Standard Commodity Classification" by all concerned government agencies and instrumentalities. The commodities for the months of January to June in 2006, on the other hand, were then backtracked to enable them to classify to 2004 PSCC.

The NSO adopted a new coverage of electronic products beginning March 2003 to ensure the consistency and comparability of statistics used by several agencies in the country. The National Statistical Coordination Board (NSCB), through NSCB Resolution No. 12, series of 2002 dated 5 June 2002, approved the new coverage. This new coverage of electronics exports resulted from an interagency work participated in by the NSO, the Bureau of Exports and Trade Promotion (BETP) of the DTI, the Semiconductor and Electronics Industries of the Philippines, Incorporated (SEIPI), and the NSCB. The new coverage now includes 359 items as described in the PSCC as against to only 40 items in the previous years.

The 1993 PSCC Revised 1 (1993 PSCC Rev.1)  was used in the classification of the commodities included in the trade statistics from 1994 to 1998 while the 1989 PSCC Revised (1989 PSCC Rev.)  was used for the years 1991 to 1993 and the 1989 PSCC was employed from 1990 to 1991.

The 1977 PSCC was used from 1977 to 1990. It was basically patterned after the UN SITC, Rev. 2 and followed similar coding scheme up to the subgroup level (4-digit). Prior to 1977, the Revised Central Bank Commodity Classification Manual was used, which was an integration of the Central Bank Statistical Classification of the Philippines patterned after the original SITC.

Beginning with 1963, the rate of conversion for every independent transaction in computing the FOB peso value are the actual rates appearing on entries or as reported in the daily foreign exchange quotations of the BSP. Thus, there is no fixed rate conversion for imports and exports since the actual rate fluctuates daily. For imports, such variable rates have been used effective January 1963, whereas for the first semester of 1963, the FOB value corresponding to the dollar receipts derived from exports was computed by using the composite rate consisting of 80 percent at the free Market rate and 20 percent at the rate of two pesos to a dollar. Starting with the second half of 1963, the rate conversion has been changed to 100 percent free market rate. This latter procedure was adopted to obtain a more realistic FOB peso value and to give a true picture of the balance of trade position of the country.

The Free on Board (FOB) value is the value of the goods free on board the carrier at the frontier of the exporting country. It includes inland freight, export duty and other expenses. Ocean freight, insurance and consular fees, however, is excluded. These FOB values are obtained directly from the source documents. However, for cases where the FOB values declared in the source documents are not in US dollars, these values are converted to US dollars. The average US dollar rate for the month which is computed as the total daily rate of transactions divided by the number of working days in a month is used in converting FOB value to FOB US dollar value. For export, the average monthly dollar rate is multiplied by 0.9925 and for import, by 1.01 for adjustments. The dollar-peso average exchange rate for the year in review is 54.67 for exports and 55.63 for imports.

In addition, valuation of goods in the Philippine Foreign Trade Statistics is FOB. However, Cost-Insurance-Freight (CIF) valuation could also be determined as the data on freight and insurance are available.

Data processing is done both mechanically and manually.

Copies of import and export documents collected by NSO personnel from the customs houses in all ports and airports of entry in the Philippines are systematically controlled. Collected documents are sorted by month, by port, by single or multiple commodity entries and by value. About 100 entries are assigned with control numbers and folioed together for the convenience of coders and encoders and for easy processing of the processors. Each folio then undergoes the following stages of processing:

1. Coding - process of translating each item of information found in the source document to its equivalent alphabetic and/or numeric code in accordance with the country, commodity, exporter, handling, carrier or port classification used

2. Code Verification - process of determining the appropriateness of codes used

3. Computation - process of computing the FOB, insurance and freight values and converting each value into US dollars.

4. Computation Verification - process of checking the accuracy of computed data.

Quality control of coding and computation for both imports and exports is carried through sample verification. This method enables the verifier to decide after a number of entries have been verified whether to reject, continue or accept the folio. The number and type of errors are recorded and brought to the attention of the coder. Further training is given on pinpointed causes of errors of coders to improve the quality of their work.

Data encoding and editing are carried-out through the use of microcomputers. Inconsistent/erroneous entries are passed through several reject listings until such errors are fully corrected or rectified after which the monthly tabulations are finally generated.

Processing of electronic files provided by the BOC like Automated Export Documentation System (AEDS) and Automated Cargo Operating System (ACOS) are performed separately from the manually processed documents. For the AEDS, the data provided which is in the form of a delimited text file is converted to data base file to suit the structure of the Foreign Trade Statistics (FTS) system. Aside from this, conversion of FOB, insurance and freight values to US dollars were also performed as there are some transactions that have used other currencies. In addition, there is a need to recode the country of origin and port as both agencies used different code structure. Further validation of commodity codes are also done to ensure the accuracy of the data. In cases that commodity description does not tally with the PSCC codes or is not provided, the name of the importers or the importers' TIN is the final determinant of the commodity codes. After all these consistency checks and edits are achieved, then the modified data base file is appended to the export's master file to generate the preliminary export figure for the month.

Documents received after the cut-off dates for each month are accumulated, processed and the data are included in their respective months at the end of the calendar year. When all the monthly tabulations for a year have been completed and finalized, the annual tabulations are then prepared.