Professionals such as lawyers, doctors, engineers, architects, accountants, and film artists are required to maintain books of accounts if their gross receipts exceed ₹1.2 lakh in any of the last three years or are expected to exceed this amount in the current year. Similarly, businesses must maintain books of accounts if their turnover exceeds ₹10 lakh in any of the last three years or is expected to exceed this amount in the current year. Even if your income or turnover is below these thresholds, you may still need to maintain books of accounts if you declare income lower than the presumed income under sections 44AD, 44AE, or 44AF. Failure to maintain the required books of accounts can lead to a penalty of up to ₹25,000.