My dad got 10 years multiple visas. He had here previously. But this time he will be staying 6 months in 2007 year. Can I able claim him as dependent on tax file. If it yes then How?
Should I apply for W7 now since he is here with me or should I apply during the tax filling next year ?
. Advice me.

If you provide more than HALF of his total support for all of 2007 AND if he is here for AT LEAST 183 days, then you can claim as a dependent.

He will need to complete and sign the Form W-7 to apply for an ITIN, which must be submitted with your 2007 tax return.

If you need professional help to do this, my email address is below.

Thanks for your suggestions, it is advisable to W7 form now or during the tax filling.

The W-7 MUST be filed with your 2007 tax return. If it is submitted earlier by itself, it will likely be rejected unless you can show an over-riding need for the ITIN prior to filing your 2007 tax return.