The line of succession to the Thai throne

The Thai line of succession is governed by the 1924 Palace Law of Succession, which dictates who is eligible to succeed the monarch.

To be in the line of succession, a person has to be:

1. A man
2. Accepted by the Thai people and the Thai Royal Family
3. Not be mentally unwell, imprisoned for a serious crime, unable to be the supreme patron of Buddhism, removed from the position of Crown Prince, have a foreign consort or declared excluded from the line of succession
4. Not be a direct son of someone prohibited from the line of succession

The Constitution of Thailand differs from the 1924 Palace Law of Succession as it allows women to be in the line of succession if there is no son (Parliament has to approve said female heir).

The King has the right to appoint his heir, who will hold the title of Crown Prince of Thailand. The current monarch, Vajiralongkorn, has not yet appointed his heir. However, he only has one recognised son, Prince Dipangkorn Rasmijoti, aged 20. The young royal has long been rumoured to have intellectual disabilities that would prevent him from ascending the throne, leading many to believe that is why the King has not yet named him as Crown Prince. 

The King’s eldest daughter, Princess Bajrakitiyabha, was long considered the next in line to the throne and had been prepared to one day ascend to the throne. However, she collapsed from a heart condition in December 2022. She has been in a coma since, with reportedly no hope for recovery.

The King has one other daughter, Princess Sirivannavari, and two sisters, Princesses Sirindhorn and Chulabhorn, who could be potential successors. He also has four sons whom he disowned: Juthavachara, Vacharaesorn, Chakriwat, and Vatchrawee, as well as another sister, Ubol Ratana, who gave up her royal titles upon marriage in the 1990s.

King Rama X (as Vajiralongkorn is also known) could potentially bring one of his sons back into the royal fold to be his heir. Vacharaesorn has made trips back to Thailand and undertaken quasi-royal duties. However, he is married to an American; he publicly stated that they are divorced, but sources have said the pair never officially separated. According to the 1924 Palace Law of Succession, Vacharaesorn cannot inherit the throne while married to a foreign woman.

With no declaration from the King or the Royal Household, the line of succession in Thailand remains unclear.