In MY world, the import tax would replace, or partially-replace the personal income tax; at least to the point of creating equal dollar value. If the import tax generated 100% of the current personal income tax, the personal income tax rate would be "0%". If the import tax generated 50% of the current personal income tax, the personal income tax rate would be set to generate 50% of what it is now.
There could be some biasing to decrease the personal income tax on lower-income people, and increase it on higher-income people.
There could be some biasing to decrease the personal income tax on lower-income people, and increase it on higher-income people.