"GST (goods and services tax) was a far-reaching iconic reform related to the share of resources between the central and state governments. It is indeed a radical tax reform," Singh said at the India Economic Forum Skoch event here.
India had shifted to this new indirect tax regime from July 2017 which aims to bring down tax compliance across the country and create a large single market.
It was formed after amalgamation of 17 various central and state levies, including excise duty, service tax and value-added tax.
"Let it not be misunderstood when many critics have said that the GST is a failure. This is exactly not a failure, this in my view is an outstanding attempt to bring about a radical change in architecture of taxation which will have many multiplier gains in terms of having the simplicity of the tax structure," he said.
In September, the country's GST collection had fell sharply to a 19-month low of Rs 91,916 crore.
This was the second straight month of decline in the GST collections.
The government had collected Rs 98,202 crore as GST in August and Rs 94,442 crore mop-up in the same month a year ago.
Cumulatively, during April-September, GST collections totalled Rs 6.06 lakh crore. In comparison, tax collections in the corresponding period of the previous fiscal were Rs 5.78 lakh crore. KPM HRS