Updated: Oct 11, 2019
In any financial year, If you have dealt in high value transactions, such as investment in property, shares or mutual fund SIPs (just an illustrative list and not complete one), then these transactions are automatically reported to the income tax department by banks and other authorities through Annual Information Return (AIR). This AIR is filed by the banks directly to the concerned Commissioners of Income tax.
The income tax department keeps track of your AIR transactions through your Permanent Account Number (PAN).
PAN or Aadhar declaration is compulsory for any registration now days and since PAN - Aadhar linking is now made mandatory by Govt., Income Tax Department has every information about you faster than ever before.
Even foreign trips and Credit card transactions are now being tracked by the I.T. Officials to see whether the spend is matching with the income declared by the taxpayer in his income tax return.
Income tax return is the only document which is being declared and filed by the taxpayer. Taxpayer needs to spend enough time in preparing the Income tax return, declaring every single reportable transaction and taking utmost care in computing / timely payment of correct taxes.
Bottom line is - If the Income tax return is filed correctly, there cannot be any notice issued to you.