Much reporting on the GST is about how tax rates have changed after the rollout. You may have read that a good or service was taxed at, say15% earlier, but will be at 18% now. I suspect that these reports are comparing on the basis of sales tax and VAT in the case of goods and service tax in the case of services. Such reporting displays a lack of understanding of the fact that GST replaces many other taxes, as also of the value added nature of the tax.

Suppose that you run a shop. You have been buying a widget that incurred excise at 10%. The cost to the manufacturer, ex tax, was Rs50. With tax, you bought it for 55 rupees. Your value addition and profit came to Rs45; with a 15% sales tax on Rs 100, the widget retailed for Rs115. The tax incidence on the widget was 20/95, or 21%.

Now, the GST at 18% has been introduced, replacing all other taxes. In a perfect world that adjusts to the GST immediately, you would receive an invoice for the widget from your supplier showing a price of Rs50 and the GST of Rs9 as separate line items. This GST would not figure in your pricing decisions because you would claim it as input tax credit. Your value addition and profit would still be 45 rupees, so your widget would be priced at Rs95 pre-tax. With a GST of 18%, your widget would be priced at Rs112.1. In other words, in our perfect world, it is perfectly possible that replacing sales tax of 15% with a GST of 18% results in a reduction in price.

The real world differs from the perfect world in several crucial ways.

First, the widget in question is imaginary and I have made up the tax rates. I have only a dim understanding of what taxes used to apply at what stage, and I have no idea what the tax rates were on different products. The government has claimed that the tax rates were aimed at achieving revenue neutrality. If they are right and if they have done a perfect job of being revenue neutral on every product and service, retail prices should not change at all. Of course, it is unrealistic to expect that kind of perfection. It will take significant analysis to figure out how good or bad a job they have done on this count, and whether they have erred on the side of higher or lower revenues. But the point to note is that revenue neutrality can only be achieved if the GST is higher than or equal to the current sales or service tax.

Second, the example assumes that the shop will instantly respond to a fall in input prices with a reduction in price. In reality, it’s just as likely to keep its listed price the same and slap the 18% on top of it, and try to pocket the profits as long as market forces let it.

Third, even if the shop does want to adjust prices in response to the GST, it is unlikely to have full visibility into prices along the entire supply chain. The example of the widget was a deliberately simplified one. The more realistic scenario is a complex supply chain with multiple stages involved in the conversion of raw materials to finished goods. Each participant in the supply chain faced a certain set of taxes earlier and is faced with GST and input tax credits now. Getting all the costs worked out and the prices renegotiated is going to take time.

Fourth, one of the avowed aims of the GST rollout is increased tax compliance. While that is a good thing, if it succeeds in achieving this goal, it means that taxes that weren’t being paid earlier are now being paid. If that happens, it means an increase in prices.

In other words, any claim you read about how the GST is going to increase or reduce prices should be taken with a pinch of salt. Unless there is evidence that those who are making the claim have done rigorous studies taking into consideration the above factors, they are probably just pulling numbers out of their ass.

A partial exception to this principle of scepticism can probably be made for services. Unlike goods, there is no supply chain to deal with, so it’s more likely that replacing a 15% service tax with GST at 18% results in a straightforward increase in price. Of course, a hairdresser’s shop does deal with raw material like shampoos and hair dyes, while for a financial services firm, the tax credit on office stationery and on ISP payments will probably not compensate for the higher GST rate.

The point of all this is that calculating the impact of the GST on prices even in the short to medium run is difficult. In the long run, the GST is supposed to bring about a whole bunch of structural changes in the economy, like speedier transport of goods, economies of scale in warehousing, more rational decision-making on the question of where to locate factories, etc. All of these should contribute to economic growth and should also have a positive impact on inflation. Calculating that impact is a different story.