Social Insurance Fund revenue come from:
1) social security contributions that are not subject to transfer to open-end pension fund;
1a) assets reimbursing the amount of contributions transferred to open-end pension funds,
1b) deposits, referred to in Art. 111c, Section 1 of legislation dated 28 August 1997 on the organisation and operation of pension funds;
2) payments from state budget and other institutions, transferred for benefits, payment of which were tasked to the Social Insurance Institution, with the exception of financial benefits from separate budget chapters and payments from foreign institutions;
3) the interest of the bank account of the Social Insurance Fund;
3a) investments made into participation units of money market funds, referred to in Art. 178 of legislation dated 27 May 2004 in regards to investment funds and management of alternative investment funds (Journal of laws dated 2020, sections 95, 695 and 2320);
3b) deposits referred to in Art. 83, Section 1, point 1 and Art. 105, Section 2, point 1 of legislation dated 4 October 2018 in regards to Employee Capital Plans;
4) the interest from late payments, overdue liabilities towards Social Insurance Fund;
5) repayments of unlawful received benefits, together with interest;
6) the additional fee, referred to in Article 24, Section 1a and from prolongation fees;
7) subsidy from the state budget;
8) assets of the Demographic Reserve Fund, referred to in Article 59 of the legislation;
9) other.

• Act of 13 October 1998 on the Social Insurance System
  Place of publication: (Dz. U. z 2021 r. poz. 423, z późn. zm.)