Updated October 18, 2026. Quick answer: Line 30 is the one place for expenses for business use of your home. You get the amount either from line 36 of Form 8829 or from the simplified method, and you cannot use both for the same home. The result is subtracted from line 29 to give the net profit or loss on line 31.
Picking the Schedule C business code for your work (2025 chart): Schedule C code for IT consultants and Schedule C code for Etsy sellers.
Picking the Schedule C business code for your work (2025 chart): Schedule C code for real estate agents and Schedule C code for child care.
Related reading on this site: IRS Publication 587.
Business use of your home (Form 8829), the saver’s credit (Form 8880), clean vehicle credits (Form 8936) and amended returns (Form 1040-X), read line by line: Form 8829 lines 1 to 7, Form 8829 lines 8 to 15 and Form 8829 lines 16 to 27.
What line 30 asks for
The form captions the line “Expenses for business use of your home. Do not report these expenses elsewhere. Attach Form 8829 unless using the simplified method.” The instructions open the same way: a taxpayer “may be able to deduct certain expenses for business use of your home, subject to limitations.” To “claim a deduction for business use of your home, use Form 8829, or you can elect to determine the amount of the deduction using a simplified method.” The form-level mechanics are on the Form 8829 page and the general topic is on the home office deduction page.
Where the number comes from: Form 8829
If you are not using the simplified method, the instructions say to “include the amount from line 36 of your Form 8829 on line 30.” In that case they also say “do not complete the additional entry spaces on line 30 for total square footage of your home and of the part of the home used for business.” Form 8829 carries the detailed expense calculation, and the instructions point to “For additional information about claiming this deduction, see Pub. 587.”
If you did not use the simplified method, the reporting rule is “include the amount from line 36 of Form 8829 on line 30 of the Schedule C you are filing for that business.”
Where the number comes from: the simplified method
The instructions describe it this way: “The simplified method is an alternative to the calculation, allocation, and substantiation of actual expenses.” The rate and size cap appear in one running sentence: “In most cases, you’ll figure your deduction by multiplying the area (measured in square feet) used regularly and exclusively for business, regularly for daycare, or regularly for storage of inventory or product samples, by $5.” They add “The area you use to figure your deduction cannot exceed 300 square feet.” Rental use is excluded: you “can’t use the simplified method to figure a deduction for rental use of your home.”
If you use it, the instructions say to “complete the additional entry spaces on line 30 for that home only.” and “Include the amount from line 5 of the Simplified Method Worksheet on line 30.” The worksheet itself, with its gross income limitation and daycare adjustment, is in the Schedule C instructions. Work through it there rather than from this page; no worksheet figure is repeated here.
Choosing the method, and the limits on switching
The instructions say you “choose whether or not to use the simplified method each tax year.” The election is made as follows: “Make the election by using the simplified method to figure the deduction for the qualified business use of a home on a timely filed, original federal income tax return for that year.” Once made, “An election for a year, once made, is irrevocable.” Moving between methods in later years is allowed: “A change from using the simplified method in one year to actual expenses in a succeeding year, or vice versa, is not a change in method of accounting and does not require the consent of the Commissioner.”
For the same home, the rule is that you “may not use the simplified method and also file Form 8829 for the same qualified business use of the same home.”
Rules the simplified method does not change
The method changes how the deduction is figured, not whether you qualify. The instructions say you “must still meet all the use requirements to claim a deduction for business use of the home.” and “The simplified method is not an alternative to the exclusivity and other tests that must be met in order to qualify for this deduction.”
The deduction is also capped by income: “The amount of your deduction is still limited to the gross income derived from qualified business use of the home reduced by the business deductions that are not related to your use of the home.” “If this limitation reduces the amount of your deduction, you can’t carry over the difference to another tax year.”
On depreciation, the instructions say “The depreciation deduction allowable for that portion of the home for that year is deemed to be zero.” Where the business use covered only part of the year or the square footage changed during the year, “your deduction is limited to the average monthly allowable square footage.”
More than one home or more than one business
For several homes, the instructions say to “Combine the amount you figured using the simplified method and the amounts you figured on your Forms 8829, and then enter the total on line 30 of the Schedule C for that business.” For several businesses: “If you used your home for more than one business, you will need to file a separate Schedule C for each business.” Where you used another home for the same business, the instructions say “If you have a business use of another home, you can’t use the simplified method for that home.”
What stays elsewhere
Two clarifications keep line 30 from double counting. For itemizers: “If you itemize your deductions on Schedule A (Form 1040), you may deduct your mortgage interest, real estate taxes, and casualty losses on Schedule A (Form 1040) as if you didn’t use your home for business.” For ordinary business costs: “Use Part II of Schedule C to deduct business expenses that are unrelated to the qualified business use of the home (for example, expenses for advertising, wages, or supplies, or depreciation of equipment or furniture).”
Where it goes next
Line 30 is subtracted from line 29. The form captions line 31 as “Net profit or (loss). Subtract line 30 from line 29.” That result is explained at Schedule C lines 31 and 32. The expense lines above line 30 are totaled on line 28, covered at Schedule C lines 27a to 29. The overall schedule is described on the Schedule C (Form 1040) page.
Edition and line numbers
This page reads the 2025 Schedule C (Form 1040) and its 2025 instructions, the current files irs.gov served on 2026-10-18. They are byte-identical to the archived copies and they are the files for the tax year 2025 return, filed in 2026. The schedule says “Attach to Form 1040, 1040-SR, 1040-SS, 1040-NR, or 1041”; “partnerships must generally file Form 1065.” Schedule C has its own instructions booklet, titled “Instructions for Schedule C” (Form 1040). Check the tax year printed on the schedule you are filling in and use the line numbers on that year’s schedule, because a different year’s schedule can number or word its lines differently.
Common mistakes
- Using Form 8829 and the simplified method for the same home. The instructions say you “may not use the simplified method and also file Form 8829 for the same qualified business use of the same home.”
- Assuming the simplified method relaxes the qualifying tests. The instructions say “The simplified method is not an alternative to the exclusivity and other tests that must be met in order to qualify for this deduction.”
- Carrying a limited deduction forward. The instructions say “If this limitation reduces the amount of your deduction, you can’t carry over the difference to another tax year.”
Related: Schedule C (Form 1040), Form 8829, home office deduction, and Form 4562.
Sources
- Instructions for Schedule C (Form 1040), Profit or Loss From Business (2025): https://www.irs.gov/pub/irs-pdf/i1040sc.pdf
- Schedule C (Form 1040), Profit or Loss From Business (2025): https://www.irs.gov/pub/irs-pdf/f1040sc.pdf
Read from the IRS documents linked above on October 18, 2026. General information, not tax advice. Your own facts decide the outcome, and a preparer, the account provider or the IRS is the right place to confirm anything consequential.