IT.act for20-21

Unless you opt for old or present tax slab rates (which you are given the choice); under new regime these deductions are not allowed

Its applicable from AY 2021.22, & yes, an individual without business income, can choose any option in any assessment year (from AY 2021-22 onward)

Yes from AY 2021-22, an individual & HUF not having any Income under the head PGBP can choose any of the 2 regime in every financial year.