Like any other transaction that makes you money, the sale of a biz is considered income and you are required by law to pay taxes on it.you need to use Form 4797 to report gain on the sale of your biz; for example, Section 1231 losses for each property are entered in Part I, line 2.Section 1231 gains for each property are entered in Part III, line 19.Part II is used to report ordinary gains and losses for certain items. However, if there is a net gain on section 1231 assets from Form 4797 , you need to report it on Sch D of 1040 as a long-term capital gain. Also if you sell Section 1245 property, biz machine, computer or etc, you must recapture your gain as ordinary income to the extent of your earlier depreciation deductions on the asset that was sold. ... If a section 1245 asset is sold at a loss, the loss is treated as a Section 1231 loss and is deducted as an ordinary loss which can reduce ordinary income Gains treated as ordinary income on the sale of section 1245 property include the lesser of depreciation and amortization on the asset, or the gain realized on the disposition.
Please visit the IRS website fo rmor einfo; https://www.irs.gov/pub/irs-pdf/i4797.pdf
also please contact an IRS Enrolled Agent /a CPA dong taxes in your lcoal area for more professional help.