Where a sale goes first. The instructions open with a table. Depreciable business property, real or tangible, held one year or less goes to Part II whether it sold at a gain or a loss. Held more than a year, the same property goes to Part III if it sold at a gain (section 1245 for equipment and other personal property, section 1250 for buildings) and to Part I if it sold at a loss. Land used in the business, held more than a year, goes to Part I. When a building and its land are sold together at a gain, the price is allocated between them by fair market value, and the building is reported in Part III and the land in Part I.
Part III computes recapture, then hands the rest on. For each property it works out the total gain from the sale price, the cost or other basis plus selling expenses, and the depreciation allowed or allowable. The ordinary income under sections 1245, 1250 and a few narrower provisions is totaled on line 31 and carried to Part II as ordinary gain; what remains, line 32, goes to Part I as section 1231 gain, except that the part from a casualty or theft goes back to Form 4684. For a residential rental or commercial building depreciated under the system in force since 1987, section 1250 recapture does not apply, so the building's whole gain normally reaches Part I. The depreciation in that gain is still unrecaptured section 1250 gain, figured on a worksheet in the Schedule D instructions, and Publication 544 notes it "cannot be more than the net section 1231 gain". Equipment and appliances are different: their depreciation is recaptured as ordinary income up to the gain.
Part I nets, and the lookback can reclassify. Line 7 combines the year's section 1231 gains and losses, including a partner's or S corporation shareholder's share from Schedule K-1 and the section 1231 results of installment sales, carried in from Form 6252, and of like-kind exchanges, carried in from Form 8824. A net loss moves to Part II and is ordinary. A net gain is reduced on lines 8 and 9 by nonrecaptured net section 1231 losses from the five preceding years; that part is ordinary income, and only the rest is entered on Schedule D as long-term capital gain.
Part II is the ordinary bucket. It takes business property held a year or less, the recapture from Part III, a net section 1231 loss, ordinary amounts from Forms 4684, 6252 and 8824, a trader's mark-to-market gains and losses, and losses on section 1244 small business stock up to the statutory ceiling of $50,000, or $100,000 on a joint return. For an individual the net result goes to line 4 of Schedule 1 of Form 1040, so an ordinary loss offsets other income without the $3,000 capital-loss limit, subject to the at-risk and passive activity rules the instructions point to.
Part IV is a different kind of recapture. If section 179 expensing was claimed on property, or depreciation on listed property such as a vehicle, and business use falls to 50 percent or less, Part IV computes how much of the earlier deduction is taken back, and the amount is reported as other income on the form or schedule where the deduction was claimed.
Investments, homes and whole businesses. Form 4797 is not the place for capital assets held for investment, which go on Form 8949 and Schedule D. Depreciable property held for investment rather than in a business is a partial exception: its recapture is figured in Part III and the excess gain goes to Form 8949. A home that was partly used for business depends on where the business part was. Publication 523 says that for space within the living area, such as a home office or a rented spare bedroom, the gain need not be allocated and the sale of that part need not be reported on Form 4797, though gain equal to depreciation allowed or allowable after May 6, 1997 still cannot be excluded. A business or rental part separate from the dwelling, such as the rented unit of a duplex the owner lived in, is reported on Form 4797. And selling a whole business is treated as selling each asset separately, with each asset's gain or loss classified and reported on its own.