Food costs were 34.2% of revenue, a decrease of 110 basis points compared to the fourth quarter of 2016. The decrease was driven by the benefit of the menu price increases, cost savings initiatives related to paper and packaging products, and relief in avocado prices during the fourth quarter of 2017 compared to the fourth quarter of 2016.
Restaurant level operating margin was 14.9% in the quarter, an improvement from 13.5% in the fourth quarter of 2016. The improvement was driven primarily by decreased promotional activity and lower food, beverage and packaging costs as a percent of revenue.
General and administrative expenses were 5.2% of revenue for the fourth quarter of 2017, a decrease of 110 basis points over the fourth quarter of 2016. In dollar terms, general and administrative expenses decreased compared to the fourth quarter of 2016 due to decreased non-cash stock-based compensation expense and lower legal costs.
Net income for the fourth quarter of 2017 was $43.8 million, or $1.55 per diluted share, compared to net income of $16.0 million, or $0.55 per diluted share, in the fourth quarter of 2016. Net income for the fourth quarter of 2017 included a $6.0 million benefit ($0.21 per diluted share) for changes in U.S. tax law.
Full year 2017 results
Revenue for the full year 2017 was $4.5 billion, up 14.7% from the prior year. The increase in revenue was driven by new restaurant openings and a 6.4% increase in comparable restaurant sales. Comparable restaurant sales for the full year included a 1.2% benefit from menu price increases during the second and fourth quarters and a 0.3% benefit from the accounting for deferred revenue during 2016 and 2017 related to Chiptopia Summer Rewards. Comparable restaurant sales improved primarily as a result of an increase in average check during 2017 compared to 2016.
We opened 183 new restaurants during the year and closed or relocated 25 (including the closure of 15 ShopHouse Southeast Asian Kitchen restaurants), bringing the total restaurant count to 2,408.
Food costs were 34.3% of revenue, a decrease of 70 basis points as compared to the prior year. The decrease was driven by the benefit of the menu price increases taken in select restaurants during the second and fourth quarters of 2017, combined with bringing the preparation of lettuce and bell peppers back into our restaurants after using pre-cut produce during portions of 2016, and cost savings initiatives related to paper and packaging products. These decreases were partially offset by higher avocado prices.
Restaurant level operating margin was 16.9% for the full year 2017, an improvement from 12.8% in the prior year. The improvement was driven by sales leverage, including the benefit of menu price increases, decreased marketing and promotional spend and labor efficiencies, partially offset by higher wages paid to crew and managers. Marketing and promotional expenses were 3.5% of revenue during 2017, compared to 5.1% of revenue during 2016.
General and administrative expenses were 6.6% of revenue for the full year of 2017, a decrease of 50 basis points over the prior year, primarily as a result of sales leverage. In dollar terms, general and administrative costs increased compared to the prior year primarily due to recording a liability of $30.0 million, which represents an estimate of potential claims and assessments by payment card networks related to the data security incident that was announced in April 2017. Additionally, increased bonus costs and higher non-cash stock-based compensation expense contributed to the increase. The increase was partially offset by lower legal costs, as well as decreased meeting costs because of the biennial All Managers Conference held in September 2016.
Our 2017 effective tax rate was 36.1%, a decrease of 4.7% from 2016, due to the enactment of the Tax Cuts and Jobs Act, and a lower state tax rate. This decrease was partially offset by federal credits on overall higher pre-tax operating income. The Tax Cuts and Jobs Act reduced the federal corporate income tax rate to 21% starting in 2018. As a result, we recognized a $6.0 million benefit related to the remeasurement of our deferred tax position at the lower rate.
Net income for the full year 2017 was $176.3 million, or $6.17 per diluted share, compared to net income of $22.9 million, or $0.77 per diluted share, for the prior year.
With regard to the impact of the Tax Cuts and Jobs Act, Jack Hartung, Chief Financial Officer, said “We’re pleased that the lower income tax rate from the tax law change will result in savings of approximately $40 to $50 million in 2018. We plan to invest more than one-third of these tax savings in our people, including by making all of our restaurant managers and crew eligible for a one-time cash bonus, awarding one-time stock bonuses to a broad group of staff employees, and enhancing a number of other benefits such as parental leave and short term disability, all to help position Chipotle as the employer of choice in the restaurant industry. We’re excited to share further details about these programs in the coming days.”