According to WIPO (world intellectual property organisation)
The PCT is an international treaty with more than 150 Contracting States.1 The PCT makes it possible to seek patent protection for an invention simultaneously in a large number of countries by filing a single "international" patent application instead of filing several separate national or regional patent applications. The granting of patents remains under the control of the national or regional patent Offices (Malaysia) in what is called the "national phase".
PCT International Pathway
Filing: you file an international application with a national or regional patent Office or WIPO, complying with the PCT formality requirements, in one language, and you pay one set of fees.
International Search: an "International Searching Authority" (ISA) (one of the world's major patent Offices) identifies the published patent documents and technical literature ("prior art") which may have an influence on whether your invention is patentable, and establishes a written opinion on your invention's potential patentability.
International Publication: as soon as possible after the expiration of 18 months from the earliest filing date, the content of your international application is disclosed to the world.
Supplementary International Search (optional): a second ISA identifies, at your request, published documents which may not have been found by the first ISA which carried out the main search because of the diversity of prior art in different languages and different technical fields.
International Preliminary Examination (optional): one of the ISAs at your request, carries out an additional patentability analysis, usually on an amended version of your application.
National Phase: after the end of the PCT procedure, usually at 30 months from the earliest filing date of your initial application, from which you claim priority, you start to pursue the grant of your patents directly before the national (or regional) patent Offices of the countries in which you want to obtain them.
PCT applicants generally pay three types of fees when they file their international applications:
(a) an international filing fee of 1,330 Swiss francs2,
(b) a search fee which can vary from approximately 150 to 2,000 Swiss francs2 depending on the ISA chosen, and
(c) a small transmittal fee which varies depending on the receiving Office.
Because an international patent application is effective in all PCT Contracting States, you do not incur, at this stage in the procedure, the costs that would arise if you prepared and filed separate applications at national and regional Offices. Further information about PCT fees can be obtained from the receiving Offices, the Fee Tables, the PCT Guide.
The fees you will need to pay as you enter the national phase represent the most significant pre-grant costs. They can include fees for translations of your application, national (or regional) Office filing fees and fees for acquiring the services of local patent agents or attorneys. In several Offices however, national filing fees are lower for international patent applications than they are for direct national applications in recognition of the work already done during the international phase. You should also remember that in the case of all granted patents, whether or not the PCT is used to obtain them, you will need to pay maintenance fees in each country in order to keep the patents alive.
For Malaysian Filers
If your application does not need international protection, then you will not need to file throught PCT.
If however after filing in Malaysia, you want to file in other countries, then you will be allowed to do so but not exceeding 12 months from the date of your Malaysian filing.
But if you need more than 12 months for you to decide to file internationally, then you have to go for PCT as you will be given extra 30 more months (from first filing date) to do international filing.