June 30, 2023 were $1,190.3 million, representing an increase of $100.1 million, or 9.2%, from $1,090.2 million for the year ended June 30, 2022. This increase in expense was due to hiring of personnel in growth states and salary increases. Instructional costs and services expenses were 64.8% of revenues during the year ended June 30, 2023, an increase from 64.6% for the year ended June 30, 2022.
Selling, general, and administrative expenses. Selling, general and administrative expenses for the year ended June 30, 2023 were $481.6 million, representing an increase of $41.8 million, or 9.5% from $439.8 million for the year ended June 30, 2022. The increase was primarily due to an increase of $31.3 million in personnel and related benefit costs and $17.4 million in professional services and marketing expenses, partially offset by a decrease of $6.5 million in bad debt expense and $1.5 million in net operating lease expense. Selling, general, and administrative expenses were 26.2% of revenues during the year ended June 30, 2023, an increase from 26.1% for the year ended June 30, 2022.
Interest income (expense), net. Net interest expense for the year ended June 30, 2023 was $8.4 million as compared to $8.3 million in the year ended June 30, 2022. The increase in net interest expense was primarily due to an increase in interest expense related to our finance leases.
Other income (expense), net. Other income, net for the year ended June 30, 2023 was $15.5 million as compared to other expense, net of $1.3 million in the year ended June 30, 2022. The increase in other income, net was primarily due to the increase in our investments in marketable securities and the returns on those investments year over year.
Income tax expense. Income tax expense was $45.3 million for the year ended June 30, 2023, or 26.3% of income before taxes, as compared to $40.1 million, or 27.2% of income before taxes for the year ended June 30, 2022. The decrease in the effective income tax rate for the year ended June 30, 2023, as compared to the effective tax rate for the year ended June 30, 2022, was primarily due to the decrease in the amount of non-deductible compensation, which was partially offset by the decrease in excess tax benefit of stock-based compensation.
Comparison of the Years Ended June 30, 2022 and 2021
Revenues. Our revenues for the year ended June 30, 2022 were $1,686.7 million, representing an increase of $149.9 million, or 9.8%, from $1,536.8 million for the year ended June 30, 2021. General Education revenues decreased $6.4 million, or 0.5%, year over year. The decrease in General Education revenues was primarily due to the 8.6% decrease in enrollments, and changes to school mix (distribution of enrollments by school). Career Learning revenues increased $156.3 million, or 60.9%, primarily due to a 41.6% increase in enrollments, school mix, as well as from the acquisitions of MedCerts and Tech Elevator.
Instructional costs and services expenses. Instructional costs and services expenses for the year ended June 30, 2022 were $1,090.2 million, representing an increase of $88.3 million, or 8.8%, from $1,001.9 million for the year ended June 30, 2021. This increase in expense was due to hiring of personnel in growth states and salary increases. Instructional costs and services expenses were 64.6% of revenues during the year ended June 30, 2022, a decrease from 65.2% for the year ended June 30, 2021.
Selling, general, and administrative expenses. Selling, general, and administrative expenses for the year ended June 30, 2022 were $439.8 million, representing an increase of $15.4 million, or 3.6%, from $424.4 million for the year ended June 30, 2021. The increase was primarily due to an increase of $9.1 million in bad debt expense resulting primarily from reserves related to our investment in Tallo, Inc., $8.7 million in licensing fees, and $8.0 million in professional services and marketing expenses, partially offset by a $7.8 million decrease in personnel and related benefit costs, including stock-based compensation. Selling, general, and administrative expenses were 26.1% of revenues during the year ended June 30, 2022, a decrease from 27.6% for the year ended June 30, 2021.
Interest income (expense), net. Net interest expense for the year ended June 30, 2022 was $8.3 million as compared to $18.0 million in the year ended June 30, 2021. The decrease in net interest expense was primarily due to the adoption of ASU 2020-06 in fiscal year 2022 which resulted in the elimination of interest expense related to the debt discount of the Convertible Senior Notes.
Income tax expense. Income tax expense was $40.1 million for the year ended June 30, 2022, or 27.2% of income before taxes, as compared to $24.5 million, or 25.6% of income before taxes for the year ended June 30, 2021. The increase in the effective income tax rate for the year ended June 30, 2022, as compared to the effective tax rate for the year ended