VAT and CST will be applicable in such case. Company A will have to get registered under the relevant state VAT act and under CST act even if there is no value addition but VAT will still be applicable since its a consignment sale. Although the syatem of VAT seeks to levy tax on the valuee adition but the incidence of tax in the VAT system depends upon the transaction of sales Hence VAT registration will be required.
You might also have to apply for service tax registration if the freight paid on the edible oil exceed the prescribed limits of Rs 750 in case of individual consignment and 1500 in case of other consignments and where the consignor or the consignee satisfies any of the following conditions:
i. A factory registered under or governed by Factories Act 1948
ii. A Company formed or registered under Companies Act 1956
iii. A corporation established by or under any law
iv. A society registered under Societies Registration Act 1860 or under any law corresponding to that Act for the time being in force in any part of the country
v. A cooperative society established by or under any law
vi. A dealer of excisable goods who is registered under Central Excise Act 1944 or rules made there under
vii. A body corporate established or a partnership firm registered under any law
Income tax will have to be paid on the commission earned on such consignment sale after deducting the allowable expenses and the income will be declared as business income.
Import duty if any applicable will also be paid on the import of edible oil