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Tong Shu Calendar Reference

Auspicious Business Opening Dates for September 2027開業 · September 2027

By Master Sean Chan · Updated

This month carries Bai Lu (白露) — month flips to 酉 on September 8 (Singapore time): the BaZi calendar's sectional boundary for the month. Below is the universal Chinese metaphysics ranking of every day in September 2027 for opening a business (開市), derived from the classical Tong Shu (通書). Opening is treated as a 'beginning' — the rules favour 開 (Opening) and 建 (Establishing) officers and Yellow Dao days carrying 天德 / 月德 protection.

Top-ranked dates this month

30
days in September
24
pass hard requirements
2
rank as 上吉
5
top picks below
DateDay PillarOfficer 建除 Mansion 宿Clash 沖Class
12027-09-10乙未開 Opening斗丑 (Ox)上吉
22027-09-20乙巳成 Completing昴亥 (Pig)上吉
32027-09-03戊子定 Stabilising角午 (Horse)吉
42027-09-25庚戌除 Removing鬼辰 (Dragon)吉
52027-09-01丙戌滿 Filling翼辰 (Dragon)吉

All days in September 2027

DateDay PillarOfficerMansion ClashNotable factorsClass
2027-09-01丙戌滿翼辰 Dragon建除 滿 · 黃道吉
2027-09-02丁亥平軫巳 Snake月德合 · 建除 平 · 宿 軫吉
2027-09-03戊子定角午 Horse天德合 · 黃道吉
2027-09-04己丑執亢未 GoatFailed requirement: not_year_break大凶
2027-09-05庚寅破氐申 MonkeyFailed requirement: not_month_break大凶
2027-09-06辛卯危房酉 Rooster建除 危平
2027-09-07壬辰危心戌 Dog建除 危平
2027-09-08癸巳成尾亥 Pig建除 成吉
2027-09-09甲午收箕子 Rat宿 箕 · 黃道吉
2027-09-10乙未開斗丑 Ox月德合 · 建除 開 · 宿 斗上吉
2027-09-11丙申閉牛寅 Tiger建除 閉凶
2027-09-12丁酉建女卯 Rabbit黃道吉
2027-09-13戊戌除虛辰 Dragon宿 虛平
2027-09-14己亥滿危巳 Snake建除 滿 · 宿 危平
2027-09-15庚子平室午 Horse月德 · 建除 平 · 黃道吉
2027-09-16辛丑定壁未 GoatFailed requirement: not_year_break大凶
2027-09-17壬寅執奎申 Monkey建除 執 · 黃道吉
2027-09-18癸卯破婁酉 RoosterFailed requirement: not_month_break大凶
2027-09-19甲辰危胃戌 Dog建除 危平
2027-09-20乙巳成昴亥 Pig月德合 · 建除 成上吉
2027-09-21丙午收畢子 Rat黃道吉
2027-09-22丁未開觜丑 Ox四離 · 建除 開 · 黃道平
2027-09-23戊申閉參寅 Tiger建除 閉 · 宿 參凶
2027-09-24己酉建井卯 Rabbit宿 井 · 黃道吉
2027-09-25庚戌除鬼辰 Dragon月德吉
2027-09-26辛亥滿柳巳 Snake建除 滿吉
2027-09-27壬子平星午 Horse建除 平 · 黃道平
2027-09-28癸丑定張未 GoatFailed requirement: not_year_break大凶
2027-09-29甲寅執翼申 Monkey建除 執 · 黃道吉
2027-09-30乙卯破軫酉 RoosterFailed requirement: not_month_break大凶
Personalised next step

BaZi-Aligned Date Report — September 2027

USD 388

A personalised PDF that re-ranks every business opening-suitable day in September 2027 against your BaZi (and, for weddings/ROM, your partner’s BaZi). It surfaces:

Order the report →

See the full glossary of classical date-selection terms in the BaZi Glossary & Auxiliary Stars.

Further reading from the blog

Selected posts from Master Sean Chan's blog covering this topic and closely related ones in practice:

Frequently asked

Why isn’t my day on the list of top 5?

The top list is the universal ranking before any personal adjustment. Many couples find their best date isn’t in the top 5. Once you account for your day pillars, the right day often shifts. That’s exactly the gap the BaZi-Aligned Date Report fills.

What does 大凶 mean and can it ever be overridden?

大凶 means the day fails a hard classical requirement: 月破 (month break), 歲破 (year break), or 四離/四絕 (a quarter-day boundary). These cannot be overridden by personal alignment; they are excluded categorically. Choose another day.

Why don’t you show times here?

Hour selection is personal. The right hour depends on your day pillar and the chosen day’s element relationship to it. Publishing universal “auspicious hours” misleads readers into thinking a generic hour is safe; it isn’t. Hours are included in the personalised report.

Where do these scores come from?

The classical Tong Shu (通書) tradition: 建除十二神 (Twelve Officers), 二十八宿 (Twenty-Eight Mansions), 月德 / 天德 (monthly and yearly virtue stars), 黃黑道 (Yellow/Black Dao), and the Dong Gong (董公) per-purpose rules. We compute these directly from astronomical solar terms — no app shortcuts.

Should I open the business on the same day as my company registration?

If you can — yes. Aligning the opening with the legal incorporation compounds the day’s influence on both events. If they have to be different, prioritise the opening (the customer-facing first day) over the registration date.

Methodology

Each day’s pillar is computed from the 60 Jiazi rotation anchored against the published Tong Shu, not from any single calendar app. The BaZi year flips at Li Chun (立春) and the BaZi month flips at every sectional solar term, both calculated from VSOP87 solar-longitude data so the boundaries land on the right minute. Twelve Officers and the 28 Mansions each rotate deterministically against well-known anchors.

The per-purpose weights are Dong Gong’s (董公擇日) — adjusted where modern almanacs disagree, in favour of the Hong Kong Observatory and Taiwan CWB lineage. Auspicious stars add to the score, taboo stars subtract, the day’s officer and mansion shift it further, and Yellow Dao adds a final small bonus. The final number gets capped at 100 and mapped to one of five tiers.