The Internal Revenue Service relies on 1099s the way it does W-2s. A 1099-MISC form to small businesses and independent contractors that work for you provides a record of their income. Whether you send out a 1099 doesn't depend on whether you hired the contractor for advertising, computer repair or painting your office. What matters is the size of the bill and the legal structure of the business.
You don't need a 1099 for any advertising work your company does in-house. Employees never get 1099s, only outside contractors. You also don't send 1099-MISC forms to corporations, except for law firms and similar professionals. It's sole proprietorships, partnerships and estates who receive 1099s. The 1099 doesn't include personal spending, only business. If you take out a billboard to wish your mother a happy birthday, the billboard company doesn't get a 1099.
The cutoff for sending a 1099 for services rendered is $600. If you pay that much money to your ad agency or the printer making your fliers, the company gets a 1099-MISC. The total for the year is what counts, so it doesn't matter whether you spend, say, $600 for a single ad or 12 ads through the year at $50 each. You report all your payments to a given contractor on a single form; you don't use one 1099 for each job.
When Congress passed the federal Affordable Care Act in 2009, it made a major change to 1099 rules. Under the new law, corporations you paid $600 to would also have to receive a 1099-MISC. The business community complained this would vastly increase the paperwork involved in their bookkeeping, so the government repealed the change in 2011. You can still find articles on various business websites that report the ACA change but not the repeal. Don't be fooled -- they're out of date.
You report "nonemployee compensation" for services your company pays for in Box 7 of form 1099-MISC. One copy of the form goes to the IRS, the other to the contractor. The 1099s for this year's payments should arrive by January 31 of next year. If you screw up and don't mail the form, the IRS can penalize you $50. If you deliberately choose not to send out the form, it's a $100 penalty.