Interesting discussion indeed. @Mike H. - the tax system is not meant to make sense. It is meant to provide employment for millions of govt workers and tax accountants.
@Carlo Michelotti - the best answers are offered by @Brandon Hall, @Linda Weygant and @Frank Palomino.
I will try to summarize what my colleagues said and resolve the remaining confusion if any. I wrote blog posts about 1099s, but BP won't let me link to them from here. You can google them. So, here we go.
1. Deducting an expense and issuing a 1099 are two related but separate issues. You can always deduct labor, with or without a 1099. If you're audited, you will need to prove that the money was paid. Issuing a 1099 is an additional requirement. If you fail to do so, your expense may still be allowed, but you will be hit with heavy penalties. Yes, the IRS does pursue people for not filing 1099s.
2. You're subject to 1099 rules if you run a "trade or business." This is an infamous grey area. Flippers, wholesalers and Realtors are 100% "trade or business", there's no debate about it. Landlords who report their rentals on Schedule E (including disregarded LLCs) normally are NOT considered "trade or business." They can usually check the "not required" box on Schedule E and forget about 1099s. One exception: if you're claiming the notorious "RE Pro" status to get around limitations on deducting losses - then you absolutely become a "trade or business" and must obey the 1099 rules. If you're a landlord filing as a pass-through entity (partnership or S-corp) - then it's debatable. I recommend you stay on the safe side and assume that all pass-through entities are "trades or businesses" and are subject to 1099 rules.
3. Warning for landlords: before you quit reading and decide that 1099s are not your concern, understand that it can still backfire. Once you claim that you not a "trade or business" for 1099 purposes, the IRS can use your position against you. They can disallow your deductions for various business operating expenses, such as marketing or education. Bottom line: even if you think you don't have to file 1099s, it is a wise strategy to do it anyway.
4. Now, who do you send 1099s to? Generally, to anybody who provided you at least $600 in services during last year. The key word is "services." This is why you do not send 1099s to Home Depot: because you buy materials there, not labor. If your contractor separates labor from materials - you issue a 1099 for labor. If you contractor does NOT separate labor and materials, you issue a 1099 for the total amount. It is his problem, not yours. Besides contractors, you issue 1099s to everyone else who provided labor and services: consultants, wholesalers, stagers, accountants etc.
5. First exception: corporations. If your contractor or vendor is a corporation - no 1099s needed. However, LLCs are not corporations (most of the time) - so you do need 1099s for most LLCs. How do you know if they are a corporation? Give them Form W-9 to complete. They should check the "corporation" box and sign. If they checked the box - you're off the hook. But keep the form!
6. Second exception: electronic payments. If you pay anybody with a credit card or some form of electronic payment like PayPal - no 1099s needed for these vendors. In fact, you should NOT issue 1099s to them. If you paid them $5,000 by credit card and another $1,000 by check - then you still need to issue a 1099 for the $1,000.
7. How do you get their SSN for 1099s? They must complete Form W-9 before they start work. After you paid them - forghedaboudit. Game over, you lost. If they have brains, then will not give you SSNs, and you really should not accept them either - due to ID theft and all. They need an EIN which they can obtain for free on the IRS website. Help them if needed. No need for an LLC to get an EIN. An EIN is just a substitute for the SSN, for business purposes.
8. But they won't complete W-9. Yes, I know. This was discussed by other people on this thread. It's best to use clean contractors, for many reasons. Saving a few bucks by hiring illegal contractors or cheaters can turn out to be very expensive. You might have to deal with their shoddy work, claims for workplace injuries, and IRS penalties. In bigger cases, even with immigration enforcement. Not to mention that if they cheat on taxes, they may cheat on you. But it's your business and your decision.
9. But they will give me fake numbers. They might try. You can verify it for free though - so it's not an excuse.
10. But I have never done it. Well, start now. If the IRS catches you, at least you will show that you started following the rules. This can save you from penalties.
11. Too much work. Or too much IRS penalties - your choice. Filing 1099s can be done online for a nominal fee, sometimes for free. Google "e-filing 1099-MISC" for 3rd party providers.