More Thais than ever prefer living the single life to getting married, according to the National Economic and Social Development Council, which partly blames it on SINK.
The NESDC said on Monday 40.5% of people of reproductive age had no desire to tie the knot, an increase from 35.7% in 2017, despite the government campaigning for people to have more children in the face of an aged society.
The data was from the latest biennial Household Social-Economic Survey, carried out last year by the state planning agency.
Reproductive age is defined by the Ministry of Public Health as from 15-49 years of age.
The NESDC said the "SINK" concept was one factor influencing people to live alone, instead of being eager to have a family. SINK stands for Single Income, No Kids.
Unmarried people worked longer hours than their colleagues who had families to take care of, and their spending more time at work gave them fewer opportunities to find a partner, according to the NESDC.
It also blamed the government's make-babies policy. It was not attractive enough when compared with other countries that offered incentives such as financial support for any family that had one or more babies.
In March, the government said it planned to make this issue a national agenda item, concerned that the low birth rate and aged society would deplete the workforce, deter investment and cause the population to shrink.
The analysis by Fidelity International and BlackRock Investment Institute reported by Bloomberg on Monday also showed India and Indonesia were targeted by investors partly due to their demographics.
Birth rates in Thailand have continued to plunge, from 44 per 1,000 people in 1960 to 14 in 2000 and 10 last year, according to data from the World Bank and Thai agencies.
Thailand became a completely aged society last year when 20% of the total population was 60 years old or more, according to the Thailand Development Research Fund.
The NESDC suggested match-making platforms be created to give all single people an opportunity to meet each other. State and private offices should offer a better balance between work and lifestyle, and promote other activities for the same reason, it added.