How do I record checks written to subcontractors? Can I record it as a Cost of Labor?

You can, although you may have subcontractors who bill you for supplies as well. So a plumber who replaces a toilet and charges labor plus materials should not be posted simply as labor since that is not correct. Ask yourself, what is the end result of the work, is it equipment or building repair, or is it a capital improvement that must be depreciated? (roof, for example)

Schedule C provides line 11 Cost of Contract Labor (see instructions). Most of the time when it is labor alone, e.g. you build houses and you hire itinerant hammer swingers, it will come under this classification. But the same scenario you hire an electrician to wire the house and it is more than just labor. Not the best example since all costs related to building a house will be cost of goods sold