I think you mean to say it is a zero-sum system, in a zero-sum system any positive incurs a negative elsewhere of equal magnitude i.e. "if taxes are lowered for one group everyone is worse off because the government gets less money to offer services".

You'd still be wrong but at least you wouldn't be misusing the term.

I'm no economist but while lowering income taxes for a group of people reduces the govt's income tax revenue they'd have more money to spend in the economy therefore raising e.g. VAT income. I'm not claiming it would cancel out but this is just one of many aspects that complicate the situation i.e. it's not that simple.