A negative tax is a subsidy, no?

In Pakistan, electricity rates are slabbed. 0-100 units are charged very little - often below cost of providing the electricity. 100-200 units more, etc. So ultimately, high consumption users subsidize low consumption users. It makes sense because low consumption users are 'using' cheap electricity from hydropower/gas, but high consumption users are forcing the state to turn on expensive oil based power plants.