US GAAP — Core Rule
US GAAP vs IFRS — Key Differences reflects two divergent standard-setting philosophies: US GAAP applies detailed, rules-based guidance across multiple industry-specific topics, while IFRS uses a principles-based framework designed for global convergence, resulting in material differences in recognition timing, measurement, and presentation across revenue, leases, inventory, and impairments.
How US GAAP Works
Revenue Recognition (ASC 606 vs. IFRS 15)
- Both standards converge on the five-step model (identify contract, identify performance obligations, determine transaction price, allocate price, recognize revenue upon satisfaction), but US GAAP applies prescriptive guidance for licenses, warranties, and contract modifications that IFRS leaves to interpretation (ASC 606-10-25-1 vs. IFRS 15).
- US GAAP includes detailed guidance on principal vs. agent assessment; IFRS 15 is more flexible, leading to differences in revenue timing for marketplace and commission arrangements.
Lease Accounting (ASC 842 vs. IFRS 16)
- Both require lessees to recognize a right-of-use (ROU) asset and lease liability on the balance sheet, but measurement differs materially (ASC 842-20-30-1 vs. IFRS 16:22–49).
- US GAAP distinguishes between finance and operating leases; IFRS 16 applies a single accounting model, resulting in lower reported lease liabilities under US GAAP for non-finance leases.
- Operating lease payment obligations under ASC 842-20-30-8 are discounted using the incremental borrowing rate; IFRS 16 permits discount rate reassessment annually, affecting liability measurement year-over-year.
Inventory Valuation (ASC 330 vs. IAS 2)
- US GAAP permits Last-In-First-Out (LIFO) method (ASC 330-10-30-9); IFRS prohibits LIFO entirely, requiring FIFO or weighted-average cost (IAS 2:25).
- This creates permanent book-to-tax differences for US GAAP entities and significant balance sheet volatility in inflationary periods for IFRS adopters.
Impairment Testing (ASC 360/ASC 350 vs. IAS 36)
- US GAAP uses a two-step impairment test: compare carrying value to undiscounted future cash flows; if impaired, write down to fair value (ASC 360-10-35-29).
- IFRS 16 uses a one-step approach: compare carrying value directly to recoverable amount (higher of fair value less costs or value-in-use), inherently lower and more conservative (IAS 36:18–19).
- ASC 350-20-35-3 requires reversal of goodwill impairment to be prohibited; IFRS allows reversal of goodwill impairment losses if circumstances change.
Financial Instruments (ASC 321 / ASC 825 vs. IFRS 9)
- US GAAP applies the "available-for-sale" category and cost method for some equity securities; IFRS 9 mandates fair value through OCI or P&L for all financial assets (IFRS 9:B4.1.1–B4.1.29).
- Expected credit loss (ECL) modeling under ASC 326 is incurred loss–based for most entities; IFRS 9 requires forward-looking ECL, resulting in earlier allowance recognition (ASC 326-20-30-1 vs. IFRS 9:5.5.1).
US GAAP — Practical Example
Scenario: A US multinational leases a manufacturing facility for 10 years at $1M annually. Incremental borrowing rate is 5%. Facility has no residual value guarantee.
US GAAP (ASC 842) — Operating Lease
Present value of lease payments: $1M × 7.722 (PVAF at 5%, 10 years) = $7.722M
| Account | Dr | Cr |
|---|
| Right-of-Use Asset | 7,722,000 | |
| Lease Liability — Current | 476,000 | |
| Lease Liability — Non-Current | 7,246,000 | |
Year 1 payment: $1M splits as interest expense ($386K on liability balance) + principal reduction ($614K).
IFRS 16 — Single Model (same ROU asset, but annual reassessment of discount rate is permitted)
Same initial entry. However, if the entity reassesses the discount rate to 4.5% in Year 3 due to credit rating improvement, the liability remeasures upward, increasing the ROU asset and creating a non-cash charge to equity (other comprehensive income), which US GAAP does not permit.
Journal entry Year 3 (IFRS only)
| Account | Dr | Cr |
|---|
| Right-of-Use Asset | 180,000 | |
| Other Comprehensive Income | | 180,000 |
US GAAP — Common Pitfalls
- Lease vs. Service Distinction: Practitioners often misclassify service contracts (e.g., software subscriptions, vehicle fleets) as leases under IFRS 16 when they lack control of an identified asset; US GAAP ASC 842 applies the same test but with narrower industry carve-outs, creating audit disputes.
- Inventory Layer Erosion: Companies with LIFO reserves that adopt IFRS or transition to IFRS (for voluntary adoption or forced change post-JOBS Act) must reverse the reserve, creating a one-time tax charge and potentially triggering a material adjustment to opening retained earnings that auditors scrutinize heavily.
- Impairment Reversal Surprises: An IFRS-reporting company testing a long-lived asset impairment in Year 2 after a Year 1 write-down may reverse the loss if fair value recovers; US GAAP prohibits this, creating surprise volatility when comparing peer earnings and balance sheets.
US GAAP — Key Paragraphs
- ASC 606-10-25-1 — Five-step revenue recognition model (US GAAP); compare to IFRS 15:27–72 for principles-based narrative.
- ASC 842-20-30-1 — Lease liability measurement at lessee inception; contrast with IFRS 16:22–49 on unified lease model.
- ASC 330-10-30-9 — LIFO inventory valuation permitted; IAS 2:25 prohibits LIFO entirely.
- ASC 360-10-35-29 — Two-step impairment test (undiscounted cash flows then fair value); IAS 36:18–19 uses one-step recoverable amount test.
- ASC 326-20-30-1 — Incurred loss allowance model for credit losses; IFRS 9:5.5.1 mandates forward-looking ECL.
