6% assumed income under presumptive taxation scheme

Sir/Madam, It has to be noted that the Presumptive Taxation scheme under Section 44AD is informed that 6% of total receipts/Accrued income should be considered as total Income. However, the effective date was not intimated for this. Could anyone help me on whether this 6% presumption income is applicable for Financial Year 2016-17 or for assessment year 2017-18 is applicable.