Couples in Beijing who have a third child without permission will face fines as much as three times the average disposable income the previous year, according to a regulation issued by the municipal government in July.
Urbanites and people living in rural areas will be fined based on the average disposable income in their home areas.
Those who have more than three children without permission will be fined for every child over the number permitted by law, the regulation stated.
In 2016, the average disposable income of city dwellers was about 57,000 yuan (,790), while the figure for rural residents was 22,300 yuan, according to the Beijing Bureau of Statistics.
Under the revised Family Planning Law of 2016, all couples are allowed to have two children, but provincial governments have the power to formulate regulations that allow specific groups to have more.
Some couples in Beijing are allowed to have three children, such as those who have one child certified as having non-congenital disabilities and certain couples where a partner has remarried, according to a regulation on family planning adopted in the capital in March 2016.
The July regulation will see violators pay lower fines than before.
Under a regulation adopted in the capital in 2002, couples with more than one child faced fines of up to 10 times the average disposable income for the previous year. However, if their disposable income was higher than the city average in the previous year they would face fines up to 10 times their disposable income in that year.
Many regions and cities updated their regulations following the implementation of the second-child policy in 2016, with fines varying from place to place.
For example, in Liaoning province, urban residents who have an unauthorized child face fines of up to 10 times the previous year's average disposable income in their place of residence.
Many regions and cities specify additional punishments for government employees who break the laws on childbirth, while in some places, such as the provinces of Guizhou, Yunnan and Hubei, government employees also face being dismissed from their jobs.