[2] The Treasurer is charged by Article V, Section 18 of the Illinois Constitution with the safekeeping and investment of the monies and securities deposited into the state treasury.

For example, the Treasurer collects estate taxes due the state, approves the encumbrance of federal funds, offers various impact investment programs to farmers, small businesses and undercapitalized communities, and administers both escheats and unclaimed property accruing to the state.

[9][10][11][12] The Treasurer also facilitates tax-advantaged ABLE, college savings, and retirement savings programs to Illinoisans and provides a voluntary local government investment pool to Illinois' 9,600 or so counties, cities, villages, towns, school districts, and other localities.

[13][14][15][16] In addition to these routine functions, the Treasurer is concurrently an ex officio member of the State Board of Investment (ISBI), an independent state agency that oversees the investment of Illinois' public pension funds.

[17] ISBI's assets under management totaled $31.5 billion at the close of the 2024 fiscal year.