It is a pleasing irony of the trade: the person who sells advertising strategy also gets to deduct their own. But marketing consultants sit on both sides of ad accounts, their own and their clients', and the tax treatment splits exactly along that line.
Promoting your own practice is fully deductible
Advertising is one of the cleanest deductions in the code: ordinary, necessary, and rarely questioned when it promotes your actual business. For a consultant marketing themselves, that covers paid search and social campaigns for your own services, sponsored newsletter placements and podcast spots, your website's design, hosting, and landing page tools, SEO tools and content production for your own site, lead magnets and the software that delivers them, business cards and conference sponsorships, and directory or marketplace listing fees. Running ads to fill your own pipeline is not vanity spend in the IRS's eyes, it is the textbook definition of the category. There is no cap tied to results either: a campaign that flopped is exactly as deductible as one that filled your calendar.
Client ad budgets are not your write-off
The other side of the line: media spend that belongs to a client's campaigns. How it is handled depends on how the money flows. In the cleanest setup, the client's card sits on the ad account and platform charges never touch your books at all, there is nothing to deduct and nothing to report. If you front the spend and the client reimburses you, the defensible treatments are either to exclude the reimbursement from income and skip the deduction, or to book the reimbursement as income and deduct the matching spend; both net to zero profit, but pick one method and apply it consistently, because mixing them creates phantom income or phantom losses. What you cannot do is deduct client ad spend you were made whole on as if it were your own marketing.
Consultants who resell media at a markup, charging the client $10,000 for $8,000 of spend, are in a different position: the full amount billed is income and the $8,000 is a deductible cost, leaving the margin taxable. That is a legitimate model, it just needs books that show both sides.
Line 8 of Schedule C, and the records that back it
Your own promotional spend lands on Schedule C, which carries a dedicated advertising line, and it reduces both income tax and the 15.3% self-employment tax on your profit. The recordkeeping is easy to get right at the source: keep your own ad accounts in your business's name on your business card, and keep client accounts in theirs. Download platform invoices monthly, they disappear from some dashboards after account changes, and tag spend by purpose in your bookkeeping so your own marketing never blends with pass-through client budgets. When your books mirror the ownership of each ad account, the deduction takes care of itself, and a client dispute or an IRS question five years later is answered with an invoice folder instead of archaeology.