To which state do i have to comply with

dear all,

I a Co in Kerala gave a contract of rebuiilding/ upgrading an hospital, situated in tamilnadu to a builder based at Delhi,

all payment to the delhi builder will be made by me from kerala,

Now the concern is the "wrks contract ", to which state VAT Laws do i have to comply with whether

of Kerala from where payment is made, or

of Delhi from where the builder operates, or

of TN where the actual work is going on,

kindly clarify me .