Explanation:

Land tax was the primary source of the government revenue. The Brahmadeya and Devadhana lands were exempted from tax.
Learning: This is a lateral explanation and deals with aspects other than those mentioned in the question, because detailing the topic at hand is not of much use.The Pallavas had a well organized administrative system. The Pallava state was divided into Kottams. The Kottam was administered by officers appointed by the king.It was also the responsibility of the central government to provide irrigation facilities to the lands.Traders and artisans such as carpenters, goldsmiths, washer-men, oil-pressers and weavers paid taxes to the government.The Pallava inscriptions throw much light on the village assemblies called sabhas and their committees. They maintained records of all village lands, looked after local affairs and managed temples.