Goods that enter Mexico via courier companies originating from countries that do not have an international treaty with Mexico will be subject to a duty of 19%, SAT said in a statement shared with reporters.

Mexico does not have an international treaty with China, where Shein and Temu are based.

Goods entering via courier companies from Canada and the U.S., which are part of the United States-Mexico-Canada trade agreement (USMCA), will be subject to a 17% duty if the value is greater than $50 but does not exceed $117.

A 19% duty will also apply to goods that exceed $1 from other countries that have international treaties with Mexico, SAT said.

The tax authority said the tariffs will strengthen the "fight against abusive practices."

Previously, countries were not required to pay duties on goods of those values, according to a SAT spokesperson.

The new measures, which go into effect on Jan. 1, come amid a slew of new tax guidelines that impact e-commerce companies, including a Dec. 19 decree by the administration of President Claudia Sheinbaum that increased import duties to as much as 35% on a swath of clothing, including dresses and shirts, home goods like blankets and curtains, as well as tents and awnings.

Officials said earlier this month that the move was aimed at preventing the importation of some products that evaded taxes, guaranteeing a level playing field for Mexican companies and protecting sector jobs.

Some industry experts have said the decree could mark a major disruption of Mexico's IMMEX program that allows foreign companies to import goods into Mexico tax-free for manufacturing, assembly or packaging for direct sale to U.S. shoppers.

E-commerce powerhouses Shein and Temu, which compete with U.S. retailers like Walmart (WMT.N) and Amazon (AMZN.O), could be particularly vulnerable to the impacts of higher tariffs.

The decree takes effect ahead of the Jan. 20 inauguration of U.S. President-elect Donald Trump, who has threatened to slap a 25% tariff on imports from Canada and Mexico.