Public opinion on individual income tax reform in China is sharply divided. As a result, the State Council is soliciting public opinion on a proposal that would raise the threshold for tax from 2,000 ($306) to 3,000 yuan a month.

While some tax experts oppose what they see as an excessive increase in the threshold, many citizens believe a rise of 1,000 yuan is far from enough, especially given high inflation.

In fact, both sides tend to mechanically interpret the threshold, believing that a fixed sum can easily generate a satisfactory outcome. Both fail to understand the true purpose of a personal income tax.

It is common sense that the most essential function of tax is to narrow income disparity and redistribute wealth between the rich and the poor, thus minimizing the resentment of the latter toward the former and building a fairer society.

To live up to this aim, more tax should be collected from the wealthy than from the middle class, and the poor should pay little or no tax. The tax should only be levied on income that isn't necessary spending on everyday necessities like food and clothing, and on raising children or supporting the elderly.

Most countries and regions have count these factors into the threshold. In Japan, a couple whose parents live with them enjoys a higher threshold than other couples, and a couple with a jobless partner also pays less income tax than one where both couple are working. Thresholds are different depending on taxpayers' circumstances.

In China, however, individuals with the same salary pay the same tax, regardless of anything else going on in their lives. Someone whose wife is unemployed pays the same as one whose wife has a decent job, and someone whose child is handicapped also pays the same as one whose child is healthy, as long as their salaries are the same.

To make the tax fairer, these factors need to be taken into consideration. Devising a more flexible and humane system far outweighs debating which fixed threshold should be adopted.