Income from other sources

Hello,

My wife has some earnings regularly from her sale in paintings and giving some tuition to school kids.

Her income per month is about 30-40 K which she gets in cash. I have the following questions:

1) I want to treat this money as her genuine income (not black) so what are the implications of her depositing this money in her savings/FD account. How will she justify her source of income?

2) Does she need to file her income tax and are all the clauses of taxes and deductions are applicable to her?

Please advice, appreciate it.

Thanks, Pradeep