A draft amendment proposing to prolong medical insurance contributions by another 10 years in Shenzhen has stirred controversy.

According to draft regulations published by the Legislative Affairs Office of Shenzhen, those who retire in and after 2017 can enjoy lifetime medical insurance provided they contributed to social security for 25 years, including at least 15 years for Shenzhen’s social security.

Social security budgets are not unified in China. The central government and local governments run their own.

Current regulations stipulate that workers pay for 15 years, including 10 years in Shenzhen.

If the amendment is implemented, residents who fall short of the payments will have to make up the contribution shortfall.

"It is simply unfair," said Shenzhen resident Xu Weiping, who works with a media organization.

"The amendment means people who retire now only need to pay for 15 years, by the time I retire I will have to have paid for 25," Xu said.

"If the payout is 300 yuan ($48) a month, I will have to pay more than 30,000 yuan. If I haven't paid enough years by the time I retire, I will have to pay both my part and the part paid by my company."

In Shenzhen, an amount equal to 24 percent of an employee’s income is paid as a medical insurance contribution. The amount is shared by employee and employer on a 50-50 basis.

Shenzhen's proposed payout period is longer than Guangzhou, capital of Guangdong province, which is proposing prolonging the time from 10 to 15 years.

In Beijing, the period is 25 years for men and 20 years for women.

Nanjing, capital of East China's Jiangsu province, has the longest contribution period, 30 years for men and 25 for women.