Domestic Tariff Area (DTA) or Domestic Tariff Zone (DTZ) means an area within India that is outside the Special Economic Zones and EOU/EHTP/STP/BTP.
All the tax obligation, permission, and other requirements would be as per the regulatory and statutory requirements of the land.
The units operating under certain specific schemes such as SEZ/EOU are expected to carry out their activities within a customs bonded area. Any area which is not under the jurisdiction of a custom bonded area is called a Domestic Tariff Area
Each EOU or STP unit has a Customs Bonded Warehouse which is treated as Customs Bonded Area. If you want to move goods in or out of the said warehouse, permission from customs/excise is required. Such goods procured locally or imported attracts duty amount. These units would have imported/procured such goods on the basis of export obligations with the government. If a unit under EOU STP fulfilled such export obligation and achieved value addition, the authorities may permit the unit to sell dutiable goods to local market. So once after completion of export obligation, EOU units or STP units sell dutiable goods to Domestic Tariff Area by obtaining permission from the customs/excise authorities.
If you obtain any goods under free of duty with government schemes, you can sell the final products to domestic tariff area, once after fulfilling your export obligation with the government licensing authority.