Dear Dr. Jones,
To start with we should clearly differetiate between two terms -
1) Receipts - Gross Receipts or sales or turnover or revenue......before allowing any deduction of expenses
2) Income - Profit/Net Profit......after deducting expenses from above receipts........
Now coming to ur queries-
1) Amount mentioned in Form 16 A - The mentioned amount is "Receipt" & Not Income - It is to be shown in the first colum of Profit & Loss a/c - "Sales/ Gross receipts of business or profession"
2) Prescribed books are to be maintained u/s 44AA whereas 44AB contains the provision of Tax Audit.(where Turnover exceeds 40lacs in case of Business & 10 Lacs in case of Profession)
As per Sec 44AA - Prescribed books are required if in any one of the three years immediately preceding the previous year
if his income from business or profession exceeds 1,20,000 or
his total sales, turnover or gross receipts, in business or profession exceeds 10 lacs
Prescribed books are also required if the above limits exceeds during the first year of business/profession
3) Return filing is not at all compulsory if INCOME is less then the exemption limit Rs. 1,60,000