Regulation S-X Rule 5-03.4 names selling, general and administrative expenses as a standard caption. Companies tag the combined figure in XBRL as SellingGeneralAndAdministrativeExpense. Many split it into two lines: selling and marketing, tagged SellingAndMarketingExpense, which covers costs directly tied to promoting and selling products, and general and administrative, tagged GeneralAndAdministrativeExpense, which covers the costs of managing the company that are not linked to any product.
What goes into SG&A varies. Research and development is usually its own line, since ASC 730 requires it to be expensed and investors want to see it separately, but some companies report it within SG&A. Depreciation of offices and equipment outside production is often included, as is stock-based compensation for sales and corporate employees. Shipping and handling costs may be in cost of revenue or in SG&A depending on company policy, which the notes disclose. These choices shift costs between gross margin and SG&A, so SG&A ratios are best compared among close peers.
Analysts track SG&A as a percentage of revenue. Because much of it, such as corporate headcount and office leases, does not rise one for one with sales, a growing company should see this ratio fall over time, which widens operating margin. A rising SG&A ratio can signal heavy investment in sales capacity, weakening pricing, or costs growing out of control. The split between selling and administrative costs helps separate spending aimed at growth from overhead.