expenses in the current-year period compared to the prior-year period. As a percentage of net sales, SG&A increased by 190 basis points to 22.4% for the thirteen weeks ended December 24, 2022 from 20.5% for the thirteen weeks ended December 25, 2021 primarily as a result of higher store-related expenses and store payroll.
Income from operations. Income from operations decreased $19.7 million, or 21.4%, to $72.5 million for the thirteen weeks ended December 24, 2022 from $92.2 million for the thirteen weeks ended December 25, 2021. The decrease in income from operations was attributable to the factors noted above. As a percentage of net sales, income from operations was 14.1% and 19.0% for the thirteen weeks ended December 24, 2022 and December 25, 2021, respectively.
Interest expense. Interest expense was $2.3 million and $1.7 million for the thirteen weeks ended December 24, 2022 and December 25, 2021, respectively. The increase in interest expense in the current-year period was primarily the result of a higher debt balance in the current-year period compared to the prior-year period.
Income tax expense. Income tax expense was $17.5 million for the thirteen weeks ended December 24, 2022, compared to $21.3 million for the thirteen weeks ended December 25, 2021. Our effective tax rate was 24.9% and 23.6% for the thirteen weeks ended December 24, 2022 and December 25, 2021, respectively. The tax rate for the thirteen weeks ended December 24, 2022 was higher than the tax rate for the thirteen weeks ended December 25, 2021, primarily due to a lower tax benefit due to income tax accounting for stock-based compensation compared to the thirteen weeks ended December 25, 2021.
Net income. Net income was $52.8 million for the thirteen weeks ended December 24, 2022 compared to $69.2 million for the thirteen weeks ended December 25, 2021. The decrease in net income was primarily attributable to the factors noted above.
Thirty-Nine Weeks Ended December 24, 2022 Compared to Thirty-Nine Weeks Ended December 25, 2021
Net sales. Net sales increased $127.0 million, or 11.5%, to $1.232 billion for the thirty-nine weeks ended December 24, 2022 from $1.105 billion for the thirty-nine weeks ended December 25, 2021. Consolidated same store sales increased 1.8%. Excluding the impact of the 7.5% decrease in e-commerce same store sales, same store sales increased by 3.6%. The increase in net sales was the result of the incremental sales from new stores opened over the past twelve months and an increase of 1.8% in consolidated same store sales, which saw an increase in average unit retail prices, driven in part by inflation.
Gross profit. Gross profit increased $28.5 million, or 6.7%, to $454.7 million for the thirty-nine weeks ended December 24, 2022 from $426.2 million for the thirty-nine weeks ended December 25, 2021. As a percentage of net sales, gross profit was 36.9% and 38.6% for the thirty-nine weeks ended December 24, 2022 and December 25, 2021, respectively. Gross profit increased primarily due to higher sales. The decrease in gross profit rate of 170 basis points was driven by 120 basis points of deleverage in buying, occupancy and distribution center costs and a 50 basis-point decrease in merchandise margin rate. The decline in merchandise margin rate was driven primarily by a 90 basis-point headwind from higher freight expense, partially offset by growth in exclusive brand penetration.
Selling, general and administrative expenses. SG&A expenses increased $55.4 million, or 24.0%, to $285.7 million for the thirty-nine weeks ended December 24, 2022 from $230.3 million for the thirty-nine weeks ended December 25, 2021. The increase in SG&A expenses was primarily a result of higher store payroll, store-related expenses, and marketing expenses in the current-year period compared to the prior-year period. As a percentage of net sales, SG&A increased by 230 basis points to 23.2% for the thirty-nine weeks ended December 24, 2022 from 20.8% for the thirty-nine weeks ended December 25, 2021, primarily as a result of an increase in store-related expenses, store payroll and marketing expenses.
Income from operations. Income from operations decreased $26.9 million, or 13.7%, to $169.1 million for the thirty-nine weeks ended December 24, 2022 from $195.9 million for the thirty-nine weeks ended December 25, 2021. The decrease in income from operations was attributable to the factors noted above. As a percentage of net sales, income