situation

if you leave in the middle of the month and immediately enter the next company, the two sides will deduct tax according to their own wages, instead of stacking them together. For example, the last company paid 5000 in half a month, and according to the new tax law, the next company paid 6000. In this case, tax deduction is carried out according to 6000 instead of 11,000, is it illegal to do so?!?.