Rich nations are bracing for China to seek exemptions from a global minimum corporate tax, a potential stumbling block for governments racing to reach wider international consensus on the plan next month.

Some officials see China as not easily signing on to the global minimum tax rate of at least 15% endorsed by Group of Seven finance ministers last week, people familiar with the discussions said on condition of anonymity because of the sensitivity of the talks.

China has a basic corporate tax rate of 25% for most companies, but reductions for high-tech sectors and for investment in research and development mean effective rates can fall below 15%. Beijing will want to retain tax incentives that it sees as key for its economic development, especially in advanced technologies.

Some of its high-tech businesses are taxed “well below” 15%, and China “could propose carve-out measures for those sectors,” said Wang Zecai, a researcher at the Chinese Academy of Fiscal Sciences, a think-tank affiliated with the Ministry of Finance, who said this was his own view rather than an official position. “Other nations may do the same as they may have similar domestic policies to encourage innovation.”

Beijing has made its push into high-tech sectors, such as microchips and new energy vehicles, the center of its economic plan for the next five years as it seeks to sustain rapid economic growth despite restrictions imposed by the U.S. and some of its allies to curb China’s tech ambitions.

China’s tax concerns inject a note of caution following the G-7 agreement that ministers hailed as a landmark breakthrough. While the country isn’t a member of that club of rich nations, it is part of the broader Group of 20, whose finance ministers meet next month in Venice and are expected to try to reach a preliminary tax deal.

China’s Foreign Ministry spokesman Wang Wenbin said Monday that the country supports the multinational efforts to reach a tax consensus by the middle of the year, while stressing that the plan should be “inclusive.”

Beijing now represents the toughest hurdle in talks over the minimum tax, according to one person familiar with the discussions. It’s seeking a “carve out” or exclusion for domestic profit, which the person said would undermine the effective tax rate of 15%. The agreement could ultimately provide a limited carve-out to satisfy China but not to the extent it would undermine the minimum tax rate, the person said.

Negotiators hope the G-20 meetings in July will be followed by a more detailed agreement expected later this year in talks involving around 140 nations under the auspices of the Organization for Economic Cooperation and Development.

China is not a member of the OECD, a group of wealthy economies, but in recent years has been a participant in its discussions on global rules aimed at preventing multinationals from shifting their profits into low-tax jurisdictions.

Pascal Saint-Amans, head of the OECD’s Center for Tax Policy, suggested in April that China’s concerns around retaining tax incentives for investment could be accommodated.

U.S. Treasury Secretary Janet Yellen, speaking at a press conference after the G-7 gathering in London on Saturday, made comments that could refer to nations that decline to sign on to the minimum tax. She said the measure would have an “enforcement mechanism” that “would essentially put pressure on those countries to abide by a corporate minimum tax or in essence apply it to companies that are headquartered there and currently booking profits in those countries.”

The minimum-tax initiative, designed to reduce the attractiveness of low-tax jurisdictions, is one of two parts of talks aimed at revamping the global tax system to change how much corporations pay, and to whom. The other seeks to capture profits of big technology companies such as Facebook Inc. and Amazon.com Inc., in countries where they provide services.

China is a major market for multinationals such as Apple Inc. and Microsoft Corp., and misses out on a large amount of revenue due to profit-shifting. In 2015 mainland China lost more than $51 billion, or 3% of its total corporate tax take, due to companies transferring their profits to cheaper jurisdictions, according to researchers at the University of California, Berkeley, and the University of Copenhagen.

Under the plan’s proposed profit reallocation rules, China could see a “potential tax revenue increase” if the final deal means more of multinational profits are “allocated to China than that under the existing transfer pricing rules,” said Jinyan Li, a tax law professor at Osgoode Hall Law School of York University in Canada.