The I-T department initiated the first phase of the ' Operation Clean Money ' on January 31 this year to check black money and stash funds in the wake of the withdrawal of Rs 500 and Rs 1,000 notes, the two highest value banknotes of the time, from circulation on November 8 last year. A year on since demonetisation, the Income Tax Department has picked 20,572 tax returns for "detailed scrutiny" suspecting discrepancies in incomes before and after demonetisation. Separately, they said, the department has identified one lakh "high risk" cases of alleged tax evasion for detailed investigation. According to the sources, 20,572 tax returns have been selected for detailed scrutiny after their profiles before and after democratization did not match. A scrutiny procedure in the I-T department parlance denotes submission of a volume of records and testimonials, after which the taxman or the assessing officer makes sure that the return filed is correct and the filer has not evaded any tax.