If a planet is near the boundary of a sign (0°-5° or 25°-30°), it might shift from the house it occupies in the Rashi Chart to another house in the Chalit chart.
This is where most students of astrology get stuck. Which chart is "true"? The answer is: nirayana bhava chalit chart calculator
A planet near the "Bhava Madhya" (midpoint of a house) is considered most potent. If a planet is near the boundary of