As per Hindu calendar, Dhanatrayodashi is celebrated on Ashwin Krushna Trayodashi (Thirteenth day of the dark fortnight of the month of Ashwin).
In common language this is known as Dhanteras. Businessmen worship their treasuries on this day. A commercial year comprises the period between two successive festivals of Diwali. Account books for the New Year are begun on this day.
A. Spiritual meaning
‘Wealth, due to which our life progresses smoothly, is worshipped. Here ‘wealth’ means pure wealth. In the Shrisukta the Earth, Water, Air, Fire and Sun are termed as pure wealth. Only that which has a real meaning is Lakshmi ! Else, adversity occurs due to wealth that is ill-gotten. It is a practice to buy a gold coin on the day of Dhanatrayodashi, so that there is prosperity throughout the year. Actually the accounts for the year should be submitted on the day of Lakshmi puja, which falls two days later. If the wealth available till Dhanatrayodashi is utilised for serving God, then (since it is utilised in service unto Truth) it continues to exist with us in the form of Devi Lakshmi. Wealth (that is money) should be earned slowly and steadily through hard work and truthfulness. The scriptures recommend that at least 1/6th of the earnings should be offered unto God.’ – H.H. Parashram Madhav Pande Maharaj, Sanatan Ashram, Devad, Panvel.
2. Dhanvantari Jayanti
According to Ayurved this is the birthdate of the Deity Dhanvantari. On this day Ayurvedic vaidyas (doctors) worship Shri Dhanvantari (vaidya of Deities). They distribute neem leaves and sugar as prasad to visitors. This has great significance. The neem fruit has originated from amrut (Divine nectar). Distribution of specific prasad signifies that Shri Dhanvantari is the Deity who bestows the Divine Principle. If we chew five to six neem leaves everyday, there will be no chance of suffering from any disease. Such is its importance. It is for this very reason that neem is distributed as prasad of Shri Dhanvantari.
Deity Yama is allotted the task of taking away life. None has escaped or will escape death, which will come in due time. However, to prevent untimely death, an oil lamp (or thirteen oil lamps) made of wheat flour should be lit and placed outside the house in the evening, facing southward. A lamp is never kept facing southward except on this day. Then reciting the following mantra we should pray.
मृत्युना पाशदंडाभ्यां कालेन श्यामसह ।
त्रयोदश्यांदिपदानात् सूर्यजः प्रीयतां मम ।।
Meaning : I offer these thirteen lamps to the son of the Sun Deity, so that He liberates me from the clutches of death and bestows His blessings.