The basic endowment insurance fund is mainly funded by individual employees, enterprises and the state. In different countries, the basic endowment insurance financing methods of tripartite financing are embodied in different forms. Individual employees' contributions to the fund can take the form of absolute amount or insurance rate, the latter is often the main form of realization. Not only that, the insurance premium rate of individual workers can be uniform, and it can also be different with different wage and income levels. In addition, the individual's payment under a certain insurance rate is often calculated on the basis of his salary income, regardless of other income items of workers. However, not all workers' wages are used as the base for calculating contributions.

Many countries stipulate the upper and lower limits of wage payment. If the wage income is below the lower limit, the old-age insurance premium will not be paid, and the part with income above the upper limit will also be exempted from the insurance premium, but the part above the upper limit will not be used as the base for future treatment.

The enterprise's contribution to the fund is generally determined by the insurance premium rate of the enterprise and the total wages of the enterprise, which is listed as the product cost of the enterprise and often charged before the enterprise pays the income tax. The insurance premium paid by the enterprise constitutes an integral part of the labor cost at the cost of 1 month. The sum of employees' individual insurance premium rate and enterprise insurance premium rate constitutes the total insurance premium rate of the national basic old-age insurance fund.

The state's contribution to the formation of the basic old-age social insurance fund can be manifested in two ways: one is indirect policy assistance; The second is to make direct financial contribution to the endowment insurance fund. Policy support is mainly through tax and interest rate policies. The support of tax policy is that endowment insurance premium is extracted according to pre-tax income. In this way, some employees and enterprises are exempted from income tax, so from the perspective of national finance, some income is lost, and this income indirectly enters the endowment insurance fund. The sponsorship of interest rate policy shows that the state sets a higher interest rate for the savings of social insurance funds than the general savings, and the excess is paid by the state finance. The state directly contributes financially to the endowment insurance fund, which can be the way to set aside a part of the endowment insurance fund from the finance every year, or the way to set aside a sum of money from the finance to make up the difference when the endowment insurance fund is insufficient.

In addition to employees, enterprises and the state as the main sources of the national basic old-age insurance fund, there is another source of the old-age insurance fund, that is, the profit income from fund investment and operation is transformed into the fund again.