Presumptive income us 44 AD & audit us 44AB

one of my client's firm is having gross turnover of Rs.5200000 and they declared income less than 8%. further the income also does not exceeds the taxable limit. Whether Audit u/s 44AD is required or not? What if the last date for audit is passed n assessee filed his I.T. returns with income less than 8% without audit.! Plz help n share ur views