Dear Ajay,
1. If after deduction, Employee is below threshold limit than tax would be zero% (In both cases PAN Number available or not).
2. If Taxaable He falls is 10%, In case no PAN number availabale, Apply 20% governed by section 206AA.
3. If Taxable Slab is 20%, Same would apply. (Section 192 or 206AA both at 20%).
4. If Taxable Slab is 30%, Apply 30% (Even He does not hold PAN).
At Last- First make it for employees to hold PAN to meet requirement of etds Return for Salary, Second for more clarity read this year circular on TDS u/s 192, Circular No. 05/2011 dated 16.08.2011, as quoted in earlier replies also, there are some clarities here like in case of Salary from more than one employer etc.
-SsB