Tds in net salary arrangements

If the employee declares to his current employer  the income received from the previous employer also, then the current employer wud be liable to make TDS on the aggregrate payments made to the employee i.e salary recd from previous employer as well as current employer.  If the employee does not declare the income recd from his previous employer, then the employer will be liable to made TDS on the payment made by the current employer.  the employee then at the time of assessing his final tax liability in the A.Y. & if tax becomes payable then he will be reuired to pay the self-assessement tax.

I would like to have more opinions on this. Unfortunately, the income tax website is not very clear when it comes to net salary arrangements, making it confusing to define the liability of the employer for the TDS payments.