IRS “Placed in Service”: Definition, Conventions, and Deductions

For IRS purposes, the placed in service date is the day property is ready and available for its intended use, not necessarily the day you bought it or first turned it on.¹ That date starts the clock on depreciation, sets which first-year convention you must use, and controls whether an asset qualifies for bonus depreciation or Section 179 in a given tax year. Get it wrong and the error ripples through every year of the recovery period.

What “Ready and Available” Means

The IRS defines property as placed in service when it is in a condition of readiness and availability for a specific use, whether in a business, an income-producing activity, or a personal activity.¹ The asset does not have to be generating revenue. It has to be capable of doing the job.

Publication 946 uses a rental house to illustrate the point: the house is placed in service when repairs are finished and it is advertised for rent, even before a tenant signs a lease.² A machine delivered to your facility in December but not installed and operational until February is placed in service in February, not the prior year.¹

The date holds until you retire or dispose of the property. Every depreciation calculation flows from it.

How the Date Is Set for Different Property

The standard does not change from asset to asset, but what proves readiness does.

Buildings and Real Property

For a commercial building or a residential rental, the placed in service date typically falls when construction is substantially complete and the structure is ready for its intended occupancy. A certificate of occupancy is strong evidence, even if no tenants have signed leases and interior spaces are still being fitted out for individual users. For a building you purchase rather than build, the date is when it is ready for its intended rental or business function after any necessary renovations.

Qualified Improvement Property

Interior improvements to a nonresidential building already in service get their own classification and their own placed in service date. To qualify, the improvement must be made to an interior portion of the building and cannot include enlargements, elevators, escalators, or changes to the building’s structural framework.³ The date is when the renovation work is complete and the improved space is ready for use.

Equipment and Vehicles

Machinery and equipment are placed in service when installation and any required testing are finished. A contractor who buys a truck that needs modifications does not place it in service the day of purchase; the date is the day the modifications are complete and the truck is accepted for use.¹

For a business vehicle, the date is the first day you use it for its business purpose. If you bought a car for personal use and later converted it to business use, the placed in service date for depreciation is the conversion date, not the original purchase date. Your depreciable basis in that situation is the lower of the property’s adjusted basis or its fair market value on the date you convert it.⁴

A Boundary: Section 197 Intangibles

Goodwill, trademarks, customer lists, covenants not to compete, and other Section 197 intangibles do not use a readiness test. Amortization begins in the month you acquire the intangible and runs ratably over 15 years.⁵ The acquisition date controls, not any concept of the asset being “ready.”

Why the Date Drives Your First-Year Deduction

Under MACRS, which applies to most tangible property placed in service after 1986, the placed in service date determines which convention you use, and the convention decides how much depreciation you can claim in the first and last year of the recovery period.

Half-Year Convention

Most personal property (equipment, furniture, vehicles, computers) uses the half-year convention by default. All property placed in service during the year is treated as though it entered service at the midpoint of the year, regardless of the actual month.³ You get half a year in year one and half a year in the final recovery year.

Mid-Quarter Convention

The half-year convention gets overridden if you load too many purchases into the end of the year. When the total depreciable basis of personal property placed in service during the last three months of your tax year exceeds 40% of the total depreciable basis of all personal property placed in service that year, the mid-quarter convention applies to every asset you placed in service during the year.⁶ Each asset is then treated as placed in service at the midpoint of the quarter it actually entered service. Q1 assets get a bigger first-year deduction; Q4 assets get a much smaller one. Real property, property placed in service and disposed of in the same year, and a few other categories are excluded from the 40% test.³

Mid-Month Convention

Nonresidential buildings on a 39-year recovery and residential rental property on a 27.5-year recovery always use the mid-month convention. Real property placed in service during any month is treated as placed in service at the midpoint of that month.³ A building placed in service January 3 and one placed in service January 28 get the same first-year deduction, so the month matters far more than the day.

Short Tax Years

If your tax year is shorter than 12 months (common for new businesses, S corp elections, or fiscal year changes), you cannot use the standard MACRS percentage tables. You calculate full-year depreciation, then multiply by a fraction: the number of months the property is treated as in service under the applicable convention, divided by 12.¹ The short year compresses your deduction, and the convention rules still apply on top.

Bonus Depreciation and Section 179

Both accelerated write-offs are gated on the placed in service date. Missing the date by a day can push the deduction into the following tax year.

The One Big Beautiful Bill Act permanently reinstated 100% bonus depreciation for qualified property acquired and placed in service after January 19, 2025.⁷ The placed in service requirement uses the same “ready and available” test that governs regular depreciation. Ordering equipment in December but not having it installed until January defers the entire deduction.

Section 179 lets you expense the full cost of qualifying property in the year you place it in service. For 2026, the maximum deduction is $1.25 million (inflation-adjusted annually), phasing out dollar-for-dollar when total qualifying property placed in service during the year exceeds $3.13 million.⁴ The property must be placed in service during the tax year, and business use must exceed 50%. Property that is purchased but not yet ready for its intended function by year-end does not qualify.

Listed Property and the 50% Business-Use Test

Vehicles and other assets the IRS designates as listed property carry an added requirement tied to the placed in service year. You must use the property more than 50% for qualified business purposes in the year you place it in service to claim Section 179, bonus depreciation, or accelerated MACRS rates.¹

If business use later falls to 50% or below, you have to recapture the excess depreciation, meaning the difference between what you claimed under accelerated methods and what you would have claimed using straight-line under the Alternative Depreciation System. The recaptured amount goes back into income for the year business use drops, and you switch to straight-line for the remaining recovery period.¹

What Happens If You Report the Wrong Date

A wrong placed in service date is not a one-year problem. It flows through every year of the recovery period because it drives the convention, the first-year percentage, and possibly the recovery period itself. The IRS can assess a 20% accuracy-related penalty on any resulting underpayment if it finds negligence or a substantial understatement of tax. For individuals, a substantial understatement exists when the tax shown on the return is understated by the greater of 10% or $5,000.⁸

Fixing the error is not routine. Form 3115, which handles changes in accounting method for depreciation, explicitly cannot be used to change a placed in service date.⁹ The usual path is to file an amended return for any open tax year within the three-year statute of limitations. Errors that span multiple years may require amending each year individually. Closed years cannot be amended, so the longer the wrong date sits on your books, the less of it you can fix.

Proving the Date in an Audit

The IRS will want evidence that the asset actually reached readiness on the date you claimed. What works depends on the asset:

Purchased assets: invoices, purchase agreements, delivery receipts, and shipping confirmations.
Constructed or custom-built assets: installation completion certificates, final inspection reports, and certificates of occupancy for buildings.
Vehicles: mileage logs or trip records showing the first date of business use.
Equipment requiring setup: work orders, testing sign-offs, or vendor commissioning reports confirming when the asset was operational.

Digital records are acceptable if your electronic storage system ensures accurate and complete transfer of source documents, maintains reasonable controls against unauthorized alteration, and provides an audit trail linking stored documents to your books and records.¹⁰

One point most businesses underestimate: the standard three-year record retention rule does not cover depreciable property. The IRS requires you to keep property records until the period of limitations expires for the year in which you dispose of the property.¹¹ For a nonresidential building on a 39-year recovery, that can mean holding placed in service documentation for more than 40 years. If those records are gone by the time you sell, you cannot prove your basis, your placed in service date, or the depreciation you already claimed, and any of the three can be challenged on audit.

1
Internal Revenue Service. Publication 946 (2025), How To Depreciate Property
2
Internal Revenue Service. Depreciation Reminders
3
Office of the Law Revision Counsel. 26 U.S. Code 168 – Accelerated Cost Recovery System
4
Internal Revenue Service. Instructions for Form 4562 (2025)
5
Office of the Law Revision Counsel. 26 USC 197 – Amortization of Goodwill and Certain Other Intangibles
6
eCFR. 26 CFR 1.168(d)-1 – Applicable Conventions
7
Internal Revenue Service. Additional First Year Depreciation Deduction (Bonus) – FAQ
8
Internal Revenue Service. Accuracy-Related Penalty
9
Internal Revenue Service. Instructions for Form 3115
10
Internal Revenue Service. Revenue Procedure 97-22
11
Internal Revenue Service. Topic No. 305, Recordkeeping