All goods bought and sent from foreign countries should pay import duties when they arrive on China's shores. But many online shopping services buy luxury items for domestic clients and try to evade the tax.

Tax rates for imported goods have four levels, from 10 percent to 50 percent. For example, foreign cosmetics typically have 50 percent duty tax imposed, while electronic goods such as phones, and watches, are taxed at a 20 percent rate.

Of the millions of items that pass through customs, it should be reported whether they are business goods or for personal use, although customs officers can use X-ray machines or other equipment to examine the content of the packages.

"They can easily spot dangerous items, such as bombs, but it is harder to determine goods that are sent in order to evade tax," says Gu Jun, a sociology professor at Shanghai University.

A General Administration of Customs report suggests many goods get into the country without paying the relevant taxes, thereby reducing government revenue, and further, the goods being imported may have health and safety problems.

This is why online stores should apply to be registered for foreign trading.

"Instead of implementing harsher punishments, the government should lower import duty rates," Gu says.

"Thus shoppers providing foreign purchasing services won't try to evade import duties, and in addition buyers get better prices."