Household corruption, mainly bribes people give government officials, fell by 68% over the course of 15 years, but "donations" to schools tripled during the period.
Thai parents, especially in Bangkok, give schools "donations" to secure places for their children at well-known schools. While they are not downright bribes, large enough sums tend to get parents what they want.
Thairath Online reported the Land Department and the National Police Office retained the lead as the agencies soliciting the most bribes, according to a study.
The study, conducted by Chulalongkorn University's Faculty of Economics, found parents' donations to schools under the Office of the Basic Education Commission or state schools, tripled to 640 million baht in 2013 from 1999.
Pasuk Phongpaichit, who led the study, found household corruption dropped by 10.46 billion baht in 2013 from 15.40 billion baht in 1999.
Financed by Thailand Research Fund, the 2013 study was based on a survey on heads of 6,000 households nationwide, up from 4,000 subjects in 1999, to gauge corruption trends and changes.
In 1999, the top agencies where officials solicited the most bribes from people who contacted them were the Land Department (5.1 billion baht), National Police Office (4.8 billion), Revenue Department (3.5 billion baht), Land Transport Department (662 million) and Customs Department (523 million), totalling 14.58 billion baht.
In 2013, the top two remained the same, but with 1.92 billion and 1.79 billion baht respectively. The third rank was government schools, with 640 million baht, followed by the Land Transport Department (190 million) and local administrative organisations (159 million).
People tend to pay land officials to help speed up approval processes and land transport officials for licence approvals.
"When inflation was taken into consideration, we can safely conclude that household corruption dropped to a third of what it was 15 years ago," said Prof Pasuk.
"The Land Department and the police kept their places even though the value shrank might be due to their far-flung authority and duties, which involve large amount of money," she said.
The declining total reflected agencies were keen about the issue and improved their processes for more transparency. Among the measures were enhancing efficiencies, trimming service steps, evaluating of services by outsiders and setting up ethics committees manned by independent members.
"However, we estimate the value might have been lower than what it actually was because we asked household heads about what they paid in cash only, not in other form of payments. Besides, the survey did not include what members of a household had paid. It also definitely doesn't reflect graft at a macro scale, like corporate corruption," Prof Pasuk said.