Budh (Mercury) mahadasha for Simha (Leo) Moon sign

In the Vimshottari system a life moves through nine long periods, each ruled by one planet. The planet that rules the period sets the tone of those years: the areas of life that come forward, and the kind of effort that pays.

The Mercury mahadasha lasts 17 years in full. Most people meet it partway through, so the part they live through can be shorter.

Mercury stands for thinking, speech, learning, trade and writing. Its period tends to favour study, skills, business and anything that runs on communication and quick judgement.

Counted from Leo as the first house, Mercury rules Virgo and Gemini, your 2nd and 11th houses. During its period the matters of both come forward:

The 2nd house is money, savings, speech and family. Its lord's period tends to bring attention to earning and saving, to what you say and how, and to the family you live with.

The 11th house is income, gains, friends and hopes. Its lord's period tends to bring returns on earlier effort, helpful networks and wishes moving closer.

Mercury counts Sun, the lord of Leo, as a natural friend. That usually makes its period sit comfortably with your Moon sign: its themes arrive with support rather than friction.

Which mahadasha you are in, and when it began, depends on the Moon's nakshatra at the moment you were born, so it is personal to you. Even within the Mercury mahadasha, where the planet sits in your own chart and the sub-periods inside it shape the years more than your Moon sign alone.