Dear Raja
Assuming the property is self occupied, that is, used for your own residential purpose, each of your share will be computed seperately and each of you will be entiltled to the dedcution of upto Rs.1,50,000 towards interest paid. But it is necessary that the person claiming the interest decution should have borrowed and also you are required to obtain a certificate from the bank which issued the loan which normally the banks send to you annually. So, if only you have borrowed the amount from the bank, you can claim the full interest as per the certificate against the NIL value of the self occupied property in question. But, if both of you have borrowed, I don't think you have the option to claim the full amount including that of your wife's portion in your return. But then, your wife can also claim the interest against the Nil value of the self occupied property. Anyhow, if both of you are in different slab rates, there will be increased tax payout. It is not relevant as to who has paid the EMI, instead the question is who has borrowed.
Also, declaring your house property income TO YOUR EMPLOYER is optional. If you feel that they are deducting TDS more than warranted, you can stop declaring the house property income to your employer and anyway you have to file your individual return and at that time you can declare your total income including the House Propoerty Income. However, since you will get the credit for the TDS deducted, it is in total, tax neutral, in the sense, you can claim refund of any execss TDS by your employer through your ITR.
Regards
Ajay