Under the Procurement Act, three main procurement methods must be used, in accordance with the conditions stipulated:

1. General invitation method: A government agency may invite general entities that have the qualifications specified by the government agency, to submit a proposal.
2. Selection method: A government agency may invite at least three particular entities that have the qualifications specified by the government agency, to submit a proposal, unless there are fewer than three entities that meet the qualifications.
3. This method can be used if there are special circumstances or conditions – for example, an article being procured that has special characteristics or is especially complex, or must be manufactured, sold, constructed, or serviced by a highly skilled person, or which, by the nature of its use, or technical specifications, must be of a brand name.
4. Specific method: A government agency may invite one specific entity that has the qualifications specified by the government agency, to submit a proposal, or to directly negotiate a price matter that has a small budget.

This method can be used if there are special circumstances or conditions – for example, if there is only one qualified entity, or an article is to be purchased due to a disaster or epidemic, and the other two methods would lead to a delay and severe damage.

The transitory provision of the Procurement Act allows the Regulation of the Office of the Prime Minister on Procurement Via Electronic Means, B.E. 2549 (2006) (the "Electronic Procurement Regulation"), issued under the Procurement Regulations, to be applied to the extent that it is consistent with the Procurement Act, until ministerial regulations, regulations, or announcements concerning matters under the Procurement Act become effective.

The Electronic Procurement Regulation requires that the procurement of supplies and services at a value exceeding Baht 2 million must be carried out in accordance with this regulation, unless approval from the Committee on Electronic Procurement is obtained for procuring supplies or services by other methods.

Subject to the procurement method, the procurement information must be published openly at the premises of the government agency that requires the supplies or services. In addition, the agency may publish the announcement and invitation documents by other means contemporaneously.

Furthermore, the Procurement Act gives the Comptroller General's Department the duty to maintain and develop a system for procurement via electronic means, and to publish information related to procurement – for example, invitation documents, and calls for tenders – in the information network system of the Comptroller General's Department, and of the responsible government agency, in accordance with the procedures specified by the Comptroller General's Department

The link to the website of the Comptroller General's Department is: http://www.cgd.go.th/cs/internet/internet/Home.html?page_locale=en_US

Prospective bidders can be excluded from competition for a number of reasons, such as being blacklisted by government agencies. It is also possible to exclude a prospective bidder from competition through a pre-qualification process in which, for instance, prospective bidders must meet qualifications set out in the terms of reference ("TOR") or a request for a proposal ("RFP"), such as experience and registered capital of the entity.