Caah limit

Yes the penalty for violating 269ST was introduced from 1.4.2017, hence not applicable in FY 2016-17.

But the Law in FY 2016-17 was that as Rule 114B and Rule 114E of Income Tax Rules (entry no. 18), if you are making any cash sale exceeding Rs. 2Lakhs per transaction, then you need to take a copy of the PAN of buyer (PAN of parents in case buyer is minor) and if PAN is not available make them fill Form No 60 and take any other Identity proof.

And if you were liable to Income tax Audit u/s 44AB, then you were required to file the return of such specified transaction under form 61A. Non compliance to the same attracts penalties.

Mind it that for FY 2016-17 the limit of 44AB was Rs 1Crore only, even if 44AD (8% presumptive tax) was allowed till 2Crores, so even you have furnished the same u/s 44AD , here for fillinf 61A turnover of Rs. 1 crore will be considered.