Own unit as job work

Dear All,

We have two units both are central excise registered. Threre is no purchase and sale in the second unit.

The second unit is just doing a intermediate part of the manufacturing process, entire raw material is sent from our main factory following jobwork annexure system. Semi-finished goods are then returned from the unit to our main unit for further processing and sale.

All the expenses of the second unit are re-imbursed from our main factory. So there is technically no value addition.

Now my question is can we use our excise registered unit as per jobwork system or we should follow the CAS-4 system.

BR. Priyanka