How Are Tam Thai and Bát Tọa Placed, and Why Do Books Always Read Them as a Pair?

What Are Tam Thai and Bát Tọa in Tử Vi Đẩu Số?

Tam Thai and Bát Tọa are two miscellaneous stars in Tử Vi Đẩu Số (Vietnamese astrology), meaning secondary stars: they are not among the 14 main stars, nor do they belong to the group of six auspicious or six inauspicious stars. Tam Thai leans toward status, rank and being respected; Bát Tọa leans toward renown, position and recognition. Because the two stars are almost always mentioned together, researchers habitually call them the Thai Tọa set, or the Tam Thai Bát Tọa pair.

One point needs to be remembered right away: their positions are not fixed. These two stars shift according to each person's birth data, specifically according to the lunar birth month and birth day. There is no such thing as Tam Thai or Bát Tọa always sitting in one particular palace.

In the interpretive tradition, Tam Thai is classified in the auspicious star group, with the Water element, governing longevity, wisdom, support and good fortune. Bát Tọa is also an auspicious star, of Yin nature, with the Wood element, governing study, examinations, academic honours and distinction, and is described as generous and dignified in character. This five-element classification is the convention of some popular references, not a point on which all books agree, so when reading different sources you will find some places recording it slightly differently.

Why do books always read Tam Thai and Bát Tọa as a pair?

The first reason lies in how they are placed: the two stars are placed as a symmetrical pair, one counted clockwise, one counted counter-clockwise, both taking the birth day as their target. Tam Thai starts from the palace containing Ta Phu, Bát Tọa starts from the palace containing Hữu Bật. Ta Phu and Hữu Bật are themselves already a paired set of supporting stars, so their offspring also carry a paired nature.

The second reason lies in meaning: both revolve around the word "standing". Tam Thai is the sense that a person has a place, is ranked at the right level; Bát Tọa is the sense that the person sits in the right seat and is recognised by others. These two faces complement each other, and missing one makes the picture of status lopsided. The book Dau So Tinh Thanh (Volume 1, part 1) lists Tam Thai and Bát Tọa right next to each other in the group of stars placed by day, together with Ân Quang and Thiên Quý, showing that tradition still treats them as one cluster.

The third reason is interpretive practice. The book Tử Vi Kinh Nghiem, lower volume, has a passage about the configuration "Thai Tọa giap Menh", meaning the two stars standing guard on either side of the Menh palace, and treats this as a sign of eminence. Once you speak of "giap" (flanking), both stars must be present for the configuration to form; a single star standing alone cannot create that flanking posture.

How to place Tam Thai and Bát Tọa by birth day, starting from Ta Phu and Hữu Bật

The most common method, recorded in Dau So Tinh Thanh and many other references, consists of two parallel steps:

• Placing Tam Thai: take the palace that currently holds Ta Phu as day one, count clockwise through the 12 palaces, and stop when you reach the lunar birth day. The palace where you stop is the position of Tam Thai.
• Placing Bát Tọa: take the palace that currently holds Hữu Bật as day one, count counter-clockwise through the 12 palaces, and stop when you reach the lunar birth day. The palace where you stop is the position of Bát Tọa.

Because Ta Phu and Hữu Bật are placed according to birth month, the positions of Tam Thai and Bát Tọa depend on both month and day of birth. This is the point that makes this set of stars different from stars placed by a single factor alone.

Another phrasing also circulates, recorded in some references: start from the Thin palace as month 1, count clockwise to the birth month to find the Ta Phu palace, then treat that as day one and count clockwise to the birth day to place Tam Thai; similarly, start from the Tuat palace as month 1, count counter-clockwise to the birth month to find the Hữu Bật palace, then continue counting counter-clockwise to the birth day to place Bát Tọa. This method and the one above actually give the same result, differing only in whether the month-counting circuit is described separately or folded into one sentence.

An illustrative example: for a person born on the 3rd day of the 6th lunar month, counting clockwise 6 palaces from the Thin palace gives the Dau palace; treat Dau as day one, count clockwise 3 more palaces, and Tam Thai lands in the Hoi palace. This example uses exactly the principle of starting from the month and then the day, so it can be checked against the method starting from Ta Phu.

To look up a specific pair of birth month and birth day quickly, see the tables at the end of the article. Those tables are calculated using exactly the placement method that Nhật Nguyệt's Tử Vi chart-building tool uses, so the figures match the tool.

Why do books advise "you should meet both stars"?

The book Tử Vi Kinh Nghiem, lower volume, mentions the configuration "Thai Tọa giap Menh", meaning the two stars standing on either side of the Menh palace, and treats this as the foundation for eminence. The book Dau So Tinh Thanh also records the two stars in the same group, right beside each other. From this comes the traditional advice: you should meet the full pair, not just one star.

The reason is fairly easy to understand. Tam Thai and Bát Tọa are miscellaneous stars, and their meaning shifts with the context of the palace they occupy. When the full pair stands together, they form a symmetrical posture, like two pillars supporting the word "standing". When one stands alone, with no counterpart pillar, the meaning of status becomes faint and is easily overshadowed by stronger stars in the palace.

Moreover, these two stars only show their effect most clearly when there are auspicious stars supporting them across the tam phuong tu chinh (the palace itself plus its two trine palaces and the opposite palace). If around them are Ta Phu, Hữu Bật, Văn Xương, Văn Khúc, Thiên Khôi, Thiên Việt, or Lộc Tồn, Hóa Lộc, Hóa Quyền, Hóa Khoa, then status has a real foundation and position is steady. If around them are inauspicious stars, punitive stars or Hoa Ky, then the same star expresses itself as a scramble over rank and a shaky position. This is the general principle when interpreting secondary stars: do not assign one fixed meaning and apply it to every case.

The section of Dau So Tinh Thanh discussing Thái Dương and Thái Âm also states clearly that Tam Thai and Bát Tọa should meet as a full pair of twin stars to have force, and only then do they add lustre to the two bright stars, so that even when Thái Dương or Thái Âm falls into a weak position they do not lose all their light. This shows that the advice "you should meet both stars" is not a matter for the Thai Tọa set alone, but is also how old books worked when combining it with other stars.

Where do the books differ?

This is a point that needs to be stated clearly, because many variant versions circulate. On the Ly So Viet Nam forum, a member compiled three different strands of knowledge about how to place the Thai Tọa set:

• Method 1: Ta Phu counted clockwise by birth day to place Tam Thai, Hữu Bật counted counter-clockwise by birth day to place Bát Tọa. This is the method used by many references and fortune-telling software, and it also matches the description in Dau So Tinh Thanh.
• Method 2: Ta Phu counted clockwise by birth month to place Tam Thai, Hữu Bật counted counter-clockwise by birth day to place Bát Tọa. This method differs by half from method 1.
• Method 3: Placing Thai Tọa by birth hour together with Tả Hữu. This method is noted as unclear and hard to picture, so it is rarely followed.

Another member on the same forum argued against it: Thai Tọa is a paired set of stars, and having one star placed by month and one by day is hard to justify, because in Tử Vi it is rare for a pair to be placed asymmetrically like that. This person held that method 2 is most likely a typing error, "day" mistyped as "month", or a misreading of the phrase "placed by month and day of birth". On that reading, the phrase only means that to place this set of stars you must rely on both month and day of birth, not that each star takes a different factor. This is because the set is placed from Ta Phu and Hữu Bật, and Ta Phu and Hữu Bật are already placed by month, after which the birth day is used to continue counting.

Another point also sparked debate: method 3 uses the birth hour. The opposing member held that this method is unclear, so it is impossible to understand how it is placed, and that no reference so far has recorded any disagreement over how Thai Tọa is placed. Even so, since this is a record from a forum rather than a quotation from an original book, it should only be treated as a cross-checking opinion, not a general conclusion.

In principle, most current references follow method 1. The remaining variants are most likely copying errors or misreadings. But since this is a field with many different lines of transmission, a researcher should still know that variants exist, rather than assuming there is only one way.

Charts use the lunar day and month without considering solar terms

One important technical feature: the method of placing Tam Thai and Bát Tọa uses the lunar birth day and birth month, and does not consider solar terms. This differs from systems such as Bát Tự (BaZi), where the month is determined by solar terms rather than by the lunar month. So when you compare a Tử Vi chart with the Four Pillars chart of the same person, the month used to place stars may not be the same.

One also needs to note the matter of a birth day bordering the Ty hour. Many chart-building traditions advise that a person born between 23:00 and 00:00 should choose the Ty hour of the following day if looking up by lunar birth day. This convention directly affects the lunar birth day used to place Tam Thai and Bát Tọa, so it needs to be determined clearly before calculating.

How do Tam Thai and Bát Tọa affect a chart?

In the interpretive tradition, Tam Thai in the Menh palace is described as a person of firm will, an enterprising spirit, leadership ability, and someone easily trusted by superiors with heavy responsibility. On wealth, the native is said to have stable finances through personal effort and knowing how to manage money. On longevity, this site records that a person with Tam Thai in Menh usually has good health and enjoys a long life if they take care of themselves. On marriage, the site describes the romantic path as less favourable than the career, with few close friends and a tendency to marry late.

With Bát Tọa in the Menh palace, the interpretive tradition describes a person with a long square face, medium build, gentle and kind-natured, fond of charity, but sometimes blunt and hasty. On career, the site records that this person has organisational and leadership ability, easily attains high social position, and has an advantage in the fields of culture, education, media and art. On marriage, the site describes a harmonious married life. On wealth, the site notes that if Bát Tọa meets auspicious stars it brings distinction, while meeting inauspicious or ruinous stars tends toward laziness and difficulty in rising.

These descriptions should be read at the right level. This is popular reference material, not a scientific conclusion, and the sites themselves state clearly that Tam Thai and Bát Tọa are secondary stars. Their role is to add shading to a person's bearing and character, especially when accompanied by supportive auspicious stars; they do not by themselves decide a person's life. A chart with a fine Tam Thai Bát Tọa but weak main stars, or surrounded by inauspicious stars, can still meet many obstacles. Conversely, a chart without these two stars can still succeed through other configurations.

What should be considered when interpreting?

Once the positions of Tam Thai and Bát Tọa have been determined, the next step is to put them in context. Do not read these two stars in isolation; you must consider the whole tam phuong tu chinh, meaning the palace in question plus its two trine palaces and the opposite palace. This approach helps show the full picture of a person's status and recognition.

Two cases need to be distinguished. First, when the two stars travel with auspicious stars and good support, status has a real foundation, position is steady, and many people recognise it. Second, when the two stars meet inauspicious stars, punitive stars or Hoa Ky, status is unsteady and disputes over rank easily arise. The same star changes its expression entirely depending on its surroundings, so one cannot say this pair of stars is "always good" or "always bad".

One final note: these two stars show their effect most clearly when they travel together and when auspicious stars support them. If only one star stands alone, with no pair and no supporting star, its quality is fairly faint, so do not inflate it. This is also why old books advise "you should meet both stars": not because the two stars are strong enough on their own, but because they need to stand side by side to form a posture.

Which palace do Tam Thai and Bát Tọa occupy by birth month and day?

The two tables below are calculated using exactly the placement method that Nhật Nguyệt's Tử Vi chart-building tool uses. Birth days 12 days apart fall into the same palace, so each column groups two or three days. Month and day are lunar month and lunar day; for people born in a leap month, each book handles it in its own way.

Palace of Tam Thai

Palace of Bát Tọa