Applicability of VAT

Please suggest that in the under mentioned cases which state shall fix the liability for VAT ?

Case 1 : A project is executed outside Delhi in the case of  a dealer registered in Delhi. Purchases for the project is done from the state where the works contract is executed.

Case 2 : A project is executed outside Delhi by a dealer registered in Delhi. Purchases for the project is done from Delhi.

Case 3 : A project is executed outside Delhi in the case of  a dealer registered in Delhi. Purchases for the project is done from a third state (i.e. from a state outside the state where works contract is executed).

regards

Sandeep Bhatnagar