Budh (Mercury) mahadasha for Karka (Cancer) 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 Cancer as the first house, Mercury rules Virgo and Gemini, your 3rd and 12th houses. During its period the matters of both come forward:

The 3rd house is effort, courage, skills, brothers and sisters and short journeys. Its lord's period tends to reward initiative, practice and your own hands-on work.

The 12th house is spending, rest, time abroad and letting go. Its lord's period tends to bring expenses, travel or a stay away from home, and a pull towards quiet and spiritual practice.

Mercury counts Moon, the lord of Cancer, as a natural enemy. Its themes may meet some friction with your temperament, so patience and a steady routine help the period give its best.

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.