35 ILCS 200/3-65
The county assessor in counties with less than 3,000,000 inhabitants which elect a county assessor under Section 3-45 may appoint as many suitable persons as in his or her judgment are necessary to act as deputies, who shall perform the duties assigned to them by the county assessor. They shall hold their office at the will of the county assessor, and shall receive compensation determined by the assessor to be paid out of the county treasury. Such deputy assessors shall, before entering upon their duties, take the oath or affirmation prescribed for the assessors.
In counties with less than 3,000,000 inhabitants which elect a county assessor under Section 3-45, in all townships not lying completely within the limits of one city, the township assessor shall be ex-officio the deputy assessor to make the assessments in the township where he or she is elected. If, in any township, the township assessor shall not be able, by himself or herself within the time allowed by law, to make the assessment of the township, any additional deputy assessors required to make the assessment shall be residents and legal voters of that township, and shall be nominated by the township's board of trustees and appointed by the county assessor only upon that nomination. Deputy assessors so appointed shall act under the supervision of the ex-officio deputy town assessors.
35 ILCS 200/3-65