Travis Marquette
Analyst · the SEC.
Now I'd like to turn the call over to Barbara Rentler, Chief Executive Officer
Thank you, Barbara. As previously mentioned, comparable store sales declined 6% in the quarter. This decrease was driven by lower traffic, which reflects customers' increased hesitancy to shop during the upsurge of the virus. This was partially offset by an increase in the size of the average basket.
Fourth quarter operating margin was 9.5% compared to 13.3% last year. Cost of goods sold increased 125 basis points in the quarter. Our merchandise margin gain of 70 basis points was more than offset by higher costs, including freight, which increased 100 basis points due to ongoing industry-wide supply chain congestion. Buying costs were higher by 50 basis points. Occupancy delevered 30 basis points on lower sales volume. Lastly, distribution costs grew 15 basis points, primarily due to higher wages, but were mostly offset by the favorable timing of packaway expenses.
SG&A for the quarter rose 260 basis points, mainly due to the deleveraging effect from the decline in comparable store sales, higher COVID-related operating expenses and timing of incentive costs. Total net COVID-related expenses for the quarter were approximately $40 million, with a higher impact to SG&A than cost of goods sold.
Turning to our balance sheet. We exited 2020 in a strong financial position with over $5.6 billion in liquidity, which includes an unrestricted cash balance of about $4.8 billion and our $800 million revolver that remains fully available.
Now let's discuss our outlook for 2021. Our guidance and results throughout fiscal 2021 will be reported versus fiscal 2019. We believe the significant impact from the extended closure of our operations in the spring of 2020, and the ongoing headwinds caused by COVID-19 throughout last year make this a more relevant basis for comparison.
As we enter 2021, there remains limited visibility regarding the ongoing pandemic and the pace and magnitude of an economic recovery. As a result, we are providing specific guidance for only the first quarter and a general outlook for the year.
Let's move now to our first quarter guidance. As a reminder, our projections for this period are compared to the 13 weeks ended May 4, 2019. While we hoped to do better, total sales are projected to be down 1% to up 4%, with comparable store sales down 1% to down 5%. This sales guidance reflects the potential impacts of lower demand during this year's Easter selling season and ongoing supply chain congestion. Earnings per share are projected to be $0.74 to $0.86.
The operating statement assumptions that support our first quarter guidance include the following: We project operating margin to be 9.9% to 10.8% versus 14.1% in 2019. This forecast reflects the deleveraging effect from the projected decline in comparable store sales and ongoing expense headwinds from increased supply chain costs and higher wages. In addition, COVID-related expenses will remain elevated and are projected to negatively impact EBIT margins by approximately 50 basis points in the period. While we expect to continue the aggressive expansion of our 2 chains, we planned a more moderate pace of openings this year, especially in the spring.
During the first quarter, we expect to open 4 Ross and 3 dd's DISCOUNTS locations during the period. Net interest expense is estimated to be about $20 million. Our tax rate is expected to be approximately 24% to 25%. And finally, weighted average diluted shares outstanding are projected to be about 356 million.
As mentioned earlier, we are only providing a general outlook for the year at this time. From a top line perspective, with the continued rollout of vaccines, potential additional government stimulus and likely pent-up consumer demand, we expect sales trends to strengthen as we move through the year. Similar to the first quarter, though, we are projecting that operating margin relative to 2019 will continue to be affected by increased supply chain costs, higher wages and COVID-related expenses. Therefore, profitability will be well below recent historical high levels. We expect to add about 60 stores, consisting of approximately 40 Ross and 20 dd's DISCOUNTS locations.
As usual, these numbers do not reflect our plans to close or relocate about 10 older stores. Net interest expense for the year is estimated to be about $76 million. Our tax rate is projected to be approximately 24% to 25%. We are planning average diluted shares outstanding to be about 356 million. Capital expenditures for 2021 are projected to be approximately $700 million, which includes investments for our next distribution center and the resumption of projects deferred from 2020. And depreciation and amortization expense, inclusive of stock-based amortization, is forecast to be about $495 million.
Now I'll turn the call back to Barbara for closing comments.