Input Parameters and Structure of the Depreciation Simulation Schedule
This depreciation calculation tool is a simulator designed to generate an estimated schedule under the straight-line method or the 200% declining-balance method based on verified parameters entered by the user.
You configure the acquisition cost, useful life, month and year placed in service, business tax classification (corporation or sole proprietorship), corporate fiscal year-end month, depreciation method, and residual salvage value.
Asset presets for personal computers, servers, internal-use software, passenger vehicles, office equipment, and buildings serve merely as input aids for typical statutory useful lives; they do not legally determine tax asset classifications solely from names.
After entering parameters, the tool displays an itemized schedule containing the period, depreciation months, opening book value, depreciation expense, accumulated depreciation, and closing book value.
Acquisition cost is restricted to integers from 1 JPY to 1,000,000,000,000 JPY, and useful life is limited to integers between 2 and 50 years corresponding to the National Tax Agency statutory rate tables; empty inputs, non-numeric values, infinities, decimals, and out-of-range figures suppress result generation.
The simulator does not interpolate missing statutory rates using approximation formulas.
For building and internal-use software presets, the interface restricts selection exclusively to the straight-line method to reduce erroneous choices.
However, this UI control does not constitute a legal determination of the applicable statutory method for an individual asset. Users should verify acquisition timing, structural materials, operational purpose, detailed asset sub-specifications, and tax election filings, using preset values strictly as starting points for data entry.
First-Year Monthly Proration from Service Commencement to Fiscal Year-End
The first fiscal period counts months starting from the month placed in service entered on screen through the fiscal year-end, rather than the acquisition month.
The accounting year ends in the chosen closing month for corporations and in December for sole proprietorships, yielding 1 to 12 prorated months including the initial month in service.
For example, placed in service in April with a March fiscal year-end equals 12 months, in July with a March year-end equals 9 months, and in January with a March year-end equals 3 months.
Commencing service mid-month is treated as a full month. Daily pro-rata calculation is not performed.
Corporate period rows display the concluding year and month as "YYYY-MM". For instance, an asset placed in service in April 2026 with a March fiscal year-end displays "2027-03" in its first row.
Sole proprietorships display "YYYY", where the calendar year ending in December of the service year forms the first period. Rather than simply adding row numbers to the initial service year, the display reflects the true concluding fiscal year when straddling accounting periods.
This monthly proration applies exclusively to standard 12-month fiscal years. Non-standard periods—such as initial formation years, dissolution years, or shortened or extended periods due to accounting date changes—are not handled.
Furthermore, periods of non-use between purchase date and actual service placement are not automatically computed; enter the month when the asset was actually placed into business operations.
Straight-Line Method Referencing Official Rate Tables and Final Salvage Adjustments
For the straight-line method, rather than rounding the simple reciprocal of useful life on the fly, the tool directly references statutory straight-line rates from the National Tax Agency's Depreciation Rate Table for assets acquired on or after April 1, 2007.
For instance, the statutory rate is 0.334 for a 3-year useful life, 0.250 for 4 years, and 0.167 for 6 years. The full-year baseline amount is calculated as Acquisition Cost × Straight-Line Rate, and only the first year is multiplied by the ratio of service months over 12.
In this simulator, fractional yen amounts are truncated (floored) in each period.
For an acquisition cost of 300,000 JPY, 4-year useful life, straight-line method, and 12 service months, the annual baseline is 300,000 JPY × 0.250 = 75,000 JPY.
If the residual salvage value is set to 1 JPY for tangible assets, depreciation runs 75,000 JPY, 75,000 JPY, and 75,000 JPY across the first three periods, with the final row adjusted to 74,999 JPY.
Because closing book value and accumulated depreciation are displayed on the same row, you can trace the exact period where final memorandum balance adjustments take effect.
Residual value can be selected between "Tangible Assets: 1 JPY" and "Intangible Assets: 0 JPY". The internal-use software preset defaults to 0 JPY.
However, this selection does not legally establish residual salvage value based solely on asset type. Verify individual asset statutory requirements before selecting, and audit the final row of the generated table.
200% Declining-Balance Method Guaranteed Minimum Comparison and Revised Depreciation
The 200% declining-balance method utilizes the statutory depreciation rates, revised depreciation rates, and guaranteed rates prescribed by the National Tax Agency for assets acquired on or after April 1, 2012.
It does not simply double the straight-line rate or mathematically estimate rates for unlisted useful lives. Each period's pre-adjustment depreciation is calculated as Opening Book Value × Declining-Balance Rate, and the guaranteed depreciation minimum is Acquisition Cost × Guaranteed Rate.
Once pre-adjustment depreciation falls below the guaranteed minimum, the opening book value of that period is locked in as the revised acquisition cost, and Revised Acquisition Cost × Revised Depreciation Rate becomes the annual baseline.
The switching row is annotated with "Revised Depreciation Commenced."
For example, with an acquisition cost of 500,000 JPY and a 5-year useful life, the declining-balance rate is 0.400, the revised depreciation rate is 0.500, and the guaranteed rate is 0.10800.
The guaranteed amount is 54,000 JPY, yielding 200,000 JPY in year 1, 120,000 JPY in year 2, and 72,000 JPY in year 3. In year 4, opening book value of 108,000 JPY multiplied by 0.400 yields 43,200 JPY, which falls below the 54,000 JPY guaranteed threshold; thus 108,000 JPY becomes the revised acquisition cost, transitioning to revised depreciation with a 54,000 JPY baseline.
If the initial period is shorter than 12 months, the calculated annual figure is prorated by month count with fractional yen truncated.
Comparison against the guaranteed threshold is evaluated using pre-adjustment depreciation derived from opening book value times the rate.
In the terminal period, depreciation is adjusted so book value does not drop below the selected 1 JPY or 0 JPY residual floor. For a 2-year useful life, because official tax tables do not define revised rates or guaranteed rates, switching based on guaranteed minimums is not performed, adhering strictly to official schedules.
Asset Presets and Unsupported Tax and Accounting Scenarios
Even when equipment shares common designations such as "air conditioner," "signboard," or "building," statutory useful life classifications vary depending on structural components, materials, installation techniques, and operational usage.
Accordingly, presets display explicit scope descriptions and caveats, such as standalone heating/cooling equipment, metal office furnishings, or wooden commercial/residential structures.
Rather than an ambiguous uniform 10-year period, signboards provide a 3-year "Signboards & Neon Signs" option while noting that metal advertising structures belong to separate classifications with different lifespans.
The tool does not calculate legacy straight-line, legacy declining-balance, or 250% declining-balance methods based on historical acquisition dates; statutory method election filings; automated useful life classification from structure and usage; simplified formulas for used assets; capital expenditures; small-sum depreciable asset expensing; lump-sum depreciable asset provisions; SME special provisions; advanced depreciation deductions; special accelerated depreciation; sales; or asset retirements.
While corporation versus sole proprietor selection updates period labels and fiscal year-ends, it does not prescribe which depreciation method you are legally obligated to elect.
These results represent numerical estimates applying verified inputs to standard calculation rules, and do not guarantee statutory depreciation deduction limits for tax return filings.
In actual tax filings and corporate accounting, review primary National Tax Agency materials, fixed asset ledgers, and institutional accounting policies, consulting a tax office or certified tax accountant when determinations are required.
Scope of In-Browser Calculations and Methodology for Auditing Results
Schedule generation from input values executes via React client state and pure mathematical functions, without proprietary database storage, history logging, CSV/PDF export, or accounting software integration.
It features no functionality transmitting acquisition costs or useful lives to external servers. However, this does not imply that standard network activity required to deliver web pages, user client devices, browsers, or browser extensions are entirely transmission-free or infallible.
When verifying output schedules, first cross-check that period labels and month counts correspond to your actual fiscal year-ends, then confirm displayed rates and useful lives against source documentation.
Next, auditing that Opening Book Value − Depreciation Expense = Closing Book Value, previous Closing Book Value = next Opening Book Value, and Accumulated Depreciation + Closing Book Value = Acquisition Cost across each row helps detect transcription discrepancies.
For declining-balance calculations, documenting the "Revised Depreciation Commenced" row along with its prior opening book value and guaranteed threshold facilitates subsequent verification.
Because schedules are not saved in the browser, transcribe key figures into internal records along with calculation date, acquisition date, service commencement month, statutory useful life justification, depreciation method, and residual value terms.
Preserving the complete set of simulation premises rather than reusing rates in isolation ensures calculations remain reproducible and verifiable in future periods.