Form 3115: How to Change Your Business Accounting Method and Claim Catch-Up Deductions

By Yarik Yarosh, CPA ·September 5, 2026 ·6 min read

Written by Yarik Yarosh, CPA (US & Canada) September 5, 2026 · FL CPA license AC61704 · CPA Ontario

Form 3115 (Application for Change in Accounting Method) is the mechanism for changing from one accounting method to another under IRC 446. The IRS requires consistency in accounting methods from year to year, so switching methods requires either automatic consent (filing Form 3115 with the return) or advance consent (filing with the IRS and waiting for approval). The most powerful feature of a method change is the Section 481(a) adjustment, which computes the cumulative difference between the old method and the new method as if the new method had always been used. A positive 481(a) adjustment (additional income) is spread over 4 years. A negative 481(a) adjustment (additional deductions) is taken entirely in the year of change. This makes Form 3115 a significant tax planning tool: a cost segregation look-back, for example, can generate hundreds of thousands of dollars in catch-up depreciation deductions in a single year.

✓Key takeaway

Form 3115 basics:

Element	Details
Purpose	Request IRS consent to change accounting method
Two types of changes	Automatic consent (file with return) and advance consent (file with IRS, wait for approval)
Section 481(a) adjustment	Cumulative catch-up amount from the old method to the new method
Negative adjustment (deduction)	Taken 100% in the year of change
Positive adjustment (income)	Spread over 4 years (25% per year)
Filing deadline (automatic)	Attach to timely filed return (including extensions)

Common automatic method changes (no IRS approval needed):

Change	DCN Number	Section 481(a) Effect
Cash to accrual basis (if eligible for small business exception)	233	Could be positive or negative
Accrual to cash basis (if eligible for small business exception, $30M gross receipts)	233	Usually negative (deduction)
Adopt de minimis safe harbor ($2,500/$5,000 per item)	222	Usually negative
Depreciation method change (including cost segregation look-back)	7	Usually negative (catch-up depreciation)
UNICAP adoption or removal (small business exemption)	213	Varies
Change in inventory method (FIFO to LIFO, etc.)	Various	Varies
Change in revenue recognition method	Various	Varies
Repair vs. improvement (adopt repair regulations)	184	Usually negative
Change capitalization threshold for tangible property	222	Usually negative

Who can use the small business exception (cash basis, no UNICAP, no inventory):

Requirement	Threshold
Average annual gross receipts (3-year test)	$30 million or less
Applies to	Cash method, exemption from UNICAP, exemption from percentage-of-completion, simplified inventory
Entity types	All (sole prop, partnership, S-Corp, C-Corp)

How does a Form 3115 method change work in practice?

Hypothetical example

Round numbers. Three common Form 3115 scenarios:

Scenario 1: Cost segregation look-back (catch-up depreciation) A dental practice purchased a commercial building in 2021 for $800,000 (depreciable building portion). The building has been depreciated straight-line over 39 years. In 2025, the dentist commissions a cost segregation study.

Component	Amount	Original Method	New Method
5-year property (dental plumbing, electrical, flooring)	$160,000	39-year SL	5-year + bonus
7-year property (cabinetry, fixtures)	$40,000	39-year SL	7-year + bonus
15-year property (parking, landscaping)	$40,000	39-year SL	15-year + bonus
39-year property (structural)	$560,000	39-year SL	39-year SL (no change)

Section 481(a) catch-up calculation:

Item	Depreciation Claimed (2021-2024)	Depreciation That Should Have Been Claimed	Difference
5-year property ($160,000)	$16,410 (39-year SL x 4 years)	$160,000 (100% bonus in 2021)	$143,590
7-year property ($40,000)	$4,103 (39-year SL x 4 years)	$40,000 (100% bonus in 2021)	$35,897
15-year property ($40,000)	$4,103 (39-year SL x 4 years)	$40,000 (100% bonus in 2021)	$35,897
Total 481(a) adjustment			($215,384)

The dentist claims a $215,384 deduction in 2025 (negative adjustment, taken 100% in the year of change). At the 32% bracket, this saves $68,923 in federal income tax, plus SE tax savings.

No amended returns needed. The catch-up is taken entirely on the 2025 return.

Scenario 2: Cash to accrual method change A growing e-commerce business (S-Corp) with $5 million in revenue has been on the cash method. The owners want to switch to accrual to better match revenue and expenses.

Item	Cash Method (As Filed)	Accrual Method (Should Have Been)	481(a) Adjustment
Accounts receivable at year-end	Not included in income	$400,000	+$400,000 (income)
Accounts payable at year-end	Not deducted	($250,000)	($250,000) (deduction)
Prepaid expenses	Deducted when paid	Not deductible until used ($50,000 prepaid)	+$50,000 (income)
Deferred revenue	Not reported	($80,000) received but not earned	($80,000) (deduction)
Net 481(a) adjustment			+$120,000

The net positive adjustment ($120,000) is spread over 4 years ($30,000 per year in additional income). This is less painful than recognizing the entire $120,000 in one year.

Scenario 3: Adopting the de minimis safe harbor A construction company has been capitalizing and depreciating items costing $500+ (tools, small equipment, parts). The company wants to adopt the de minimis safe harbor to expense items costing $2,500 or less (or $5,000 if they have audited financial statements).

Item	Prior Method	New Method	481(a) Adjustment
Tools and small equipment (cost $500-$2,500 each)	Capitalized, depreciated over 5-7 years	Expensed immediately	Remaining undepreciated basis becomes a deduction
Total undepreciated basis of items $500-$2,500	$45,000	$0	($45,000)

The company claims a $45,000 deduction in the year of change. Going forward, all purchases of $2,500 or less are expensed immediately.

Form 3115 filing requirements:

Requirement	Automatic Consent	Advance Consent
IRS pre-approval needed?	No	Yes
Filing method	Attach to timely filed return + send copy to IRS	File with IRS, await ruling
User fee	$0	$12,100 (2025)
Processing time	N/A (automatic)	4-9 months
Scope limitation	Can only file if not under audit for the method change issue	No limitation
Duplicate filing year	Can’t file for a method already changed in last 5 years (some exceptions)	No limitation

Timing strategy:

Situation	Best Timing
Large negative 481(a) adjustment (catch-up deduction)	File in a high-income year to maximize tax savings
Large positive 481(a) adjustment (catch-up income)	File in a low-income year (4-year spread begins in that year)
Cost segregation look-back	File as soon as the study is complete
Cash to accrual conversion	Consider timing relative to AR/AP balances

Illustrative numbers only, not a real client and not advice for your facts.

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Cite this page

Yarik Yarosh, CPA. "Form 3115: How to Change Your Business Accounting Method and Claim Catch-Up Deductions." Blue Cloud CPA, September 5, 2026. https://bluecloudcpa.com/guides/small-business-form-3115-accounting-method-change

This guide is general information, not tax advice for your specific situation. Which points apply, and how, depends on your facts.