From old income tax slab to new income tax slab

You can opt for new tax system when employer ask for TDS deduction and at the time of filing of income tax return you can change your tax payment method. there are no deductions or exemptions will be available in the new system. like HRA, LTA, 80C,D,E,G etc under chapter VI A. even you can't claim interest on housing loan if loan has taken for self occupied property. but the same is available in the old system.
but relief under sec 87A is there in the both systems that is if income is below 5 lakhs then you no need to pay tax under both the systems.

Yes you can file return as per old slab

You can file the IT return under old tax regime even if the employer deducted TDS based on new tax regime
It is your choice at the time of filing of IT return to choose the tax regime based on your tax saving by comparing both the tax regimes

The option is still open to you.
go with the one which is most beneficial

Thank u all

It is your choice at the time of filing of IT return to choose the tax regime based on your tax saving by comparing both the tax regimes

Your welcome