A reader was surprised upon reviewing his SP group utility bills. Current utility bills under SP group are for Gas Services and Water Services. Electricity charges have been switched to electricity retailers under the Open Energy Market (OEM) scheme.
For the Water Services charges, the bill includes a Waterborne Fee and also a Water Conservation Tax.
However to the reader's surprise, the final utility bill is inclusive of GST. So apparently the calculation shows that GST is being charged on the Water Conservation Tax.
So it seems Singaporean households have been paying a tax on tax.