What is the problem with this arrangement?

There are two important problems with the current arrangement.

First, keep in mind that some good such as a shirt has to first be manufactured before it is consumed. The central government, therefore, levies its indirect tax called central excise at the factory gate. Subsequently, a shirt reaches a retail outlet and is bought by a consumer. The state government, at this stage, levies a tax on consumption dubbed value added tax (VAT). So, we have a tax at the factory gate which adds to the cost of the shirt and another tax on the final price.

Since states have their exclusive domain on consumption tax within their borders, they treat goods coming from other states as “imports.” For example, if a shirt maker in Uttar Pradesh buys dye in Bihar, he would have paid central excise and Bihar’s state taxes on the product. On this cost, Uttar Pradesh government would levy its tax if the shirt is sold in the state. If the shirt is sent across Uttar Pradesh’s border and sold in Delhi, an “export” tax called central sales tax is collected by UP.

As the example suggests, India is politically one country, but economically it is fragmented. There are multiple taxes when there is commerce across state borders. Consequently, it increases costs for everyone and makes economic activity within India for Indians complicated.