Business · official-source review · reviewed 2026-10-10
A home office claim starts with a share of the home, and a guessed share is the first thing a reviewer questions.
Turn the office area and the home area into a business-use share, then apply that share to the shared costs you choose.
Self-employed people who work from part of their home and want to measure the space before they talk to a tax adviser.
Use the source document or official route that applies to your situation. This guide does not contact another person or verify external information.
Measure the floor area used only for work. Write the square footage on paper.
Measure the whole home in the same units. Use the same method for both measurements.
The IRS requires regular and exclusive use for this deduction. A dining table used for work does not qualify on its own.
List the shared home costs you would allocate, such as utilities or rent, for the same year.
Read the current IRS guidance on the simplified and regular methods before you claim anything.
Your office is 120 square feet in a 1,500 square foot home. That is an 8 percent business share, so 8 percent of $2,400 in shared costs is $192.
Use your own source and details. The example is not a record about a real person or organization.
U.S. Internal Revenue Service · reviewed 2026-10-10
What this source supports: The IRS describes the simplified and regular methods for the home office deduction and the exclusive-use requirement.
Source limit: Eligibility depends on exclusive and regular use. Publication 587 has the current rules.
These sources support the statements above. They do not show that every person needs this guide. They do not show a specific result.
This guide measures a share from square footage. It does not decide whether your space qualifies, because regular and exclusive use rules apply.
Eligibility depends on exclusive and regular use. Publication 587 has the current rules.
Use current instructions from the responsible organization. This guide is a planning aid, not an official decision or a substitute for qualified advice.
Turn the office area and the home area into a business-use share, then apply that share to the shared costs you choose.
This App measures a share from the square footage you enter. It does not decide whether your space qualifies for the deduction or replace IRS guidance.
You enter every number yourself. The sources support the method and the limits. They do not produce a result for your specific case. Keep the original documents next to the sheet you build.
The App computes the worked example with your own numbers, in your browser.
APP 1
Turn the office area and the home area into a business-use share, then apply that share to the shared costs you choose.
Free · no account · no upload
Open Home Office Business-Use ShareThe App runs in this browser. It does not send or save entries. Copy, download, or print only when you choose.
This guide uses short, direct instructions as an ASD-STE100-style writing target. It is not a formal certification.
Companion App: Home Office Business-Use Share. It runs in this browser and does not upload your entries.
This guide is edited for clarity and checked against the sources it links. It is not a substitute for official instructions or qualified advice. A linked source does not show that every person needs this guide.