Deductions & credits
The difference is between Form 4562, 4562 instructions, and Pub 946. Pub 946 is very clear in the limitation. Form 4562 uses all taxable income on the return as you and your spouse are one tax entity and states that you need to use Pub 946 to determine the entry. Therefore, form 4562 will allow you to claim it all if no changes are made. Pub 946 is the authority.
About Form 4562, Depreciation and Amortization line 11 states:
Line 11
The total cost you can deduct is limited to your taxable income from the active conduct of a trade or business during the year. You are considered to actively conduct a trade or business only if you meaningfully participate in its management or operations. A mere passive investor is not considered to actively conduct a trade or business.
Note.
If you have to apply another Code section that has a limitation based on taxable income, see Pub. 946 for rules on how to apply the business income limitation for the section 179 expense deduction.
Individuals.
Enter the smaller of line 5 or the total taxable income from any trade or business you actively conducted, computed without regard to any section 179 expense deduction, the deduction for one-half of self-employment taxes under section 164(f), or any net operating loss deduction. Also, include all wages, salaries, tips, and other compensation you earned as an employee (from Form 1040, line 1). Do not reduce this amount by unreimbursed employee business expenses. If you are married filing a joint return, combine the total taxable incomes for you and your spouse.
About Publication 946, How to Depreciate Property states: Business Income Limit
The total cost you can deduct each year after you apply the dollar limit is limited to the taxable income from the active conduct of any trade or business during the year
Ultimately, it is your tax return and it sounds like you have filed the return. Use the equipment and grow a fabulous business so there are no worries in the future about the write-off.
