Accumulated Depreciation Calculator (Straight-Line)
Using the straight-line method, compute annual depreciation, accumulated depreciation to date and current book value.
輸入資料
計算結果
重點速覽：Accumulated depreciation is the total depreciation of a fixed asset from inception to date. Straight-line: annual depreciation = (cost - salvage value) / useful life; accumulated depreciation = annual depreciation x years elapsed; book value = cost - accumulated depreciation.
計算公式
每年折舊 = (資產成本 − 殘值) ÷ 可用年限。
累計折舊 = 每年折舊 × 已使用年數。
帳面淨值 = 資產成本 − 累計折舊。
$$\text{每年折舊} = \dfrac{\text{資產成本} - \text{殘值}}{\text{可用年限}}$$$$\text{累計折舊} = \text{每年折舊} \times \text{已使用年數}, \quad \text{帳面淨值} = \text{資產成本} - \text{累計折舊}$$使用說明
- Enter the asset cost and its estimated salvage value.
- Enter the useful life and years elapsed.
- View annual depreciation, accumulated depreciation and current book value.
成本 HK$1,000,000、殘值 HK$100,000、可用年限 10 年 (每年折舊 HK$90,000) 的折舊進度
| 已使用年數 | 每年折舊 | 累計折舊 | 帳面淨值 |
|---|---|---|---|
| 0 年 | HK$90,000 | HK$0 | HK$1,000,000 |
| 3 年 | HK$90,000 | HK$270,000 | HK$730,000 |
| 5 年 | HK$90,000 | HK$450,000 | HK$550,000 |
| 7 年 | HK$90,000 | HK$630,000 | HK$370,000 |
| 10 年 | HK$90,000 | HK$900,000 | HK$100,000 (=殘值) |
理財情境案例
案例一：機器用滿 3 年的帳面淨值
一部機器成本 HK$1,000,000、預計殘值 HK$100,000、可用年限 10 年。每年折舊 = (1,000,000 − 100,000) ÷ 10 = HK$90,000。
用滿 3 年後，累計折舊 = 90,000 × 3 = HK$270,000，帳面淨值 = 1,000,000 − 270,000 = HK$730,000。這正是資產在資產負債表上呈現的淨額。
案例二：折舊如何影響利潤與稅務
同一部機器每年折舊 HK$90,000 會列作費用，壓低該年的會計利潤 — 但折舊是非現金費用，公司並沒有實際支出這筆錢。
香港稅務上的『折舊免稅額』另有規則 (機械設備多採遞減折舊率)，與會計直線折舊未必相同。報稅時應以稅務局規定為準，避免直接把會計折舊當成稅務扣減。
常見問題
What is the difference between accumulated and annual depreciation?
Annual depreciation is the charge for one year; accumulated depreciation is the sum of all years' charges to date. Under straight-line, annual is fixed and accumulated is annual x years elapsed. Book value = cost - accumulated depreciation.
What is salvage value, and can it be zero?
Salvage value is the estimated recoverable value at end of life (e.g. from disposal). It can be zero, meaning the whole cost is depreciated. Higher salvage means lower annual depreciation; as an estimate it affects the amount, so judge reasonably.
Is accounting depreciation the same as tax depreciation?
Not necessarily. This tool computes accounting straight-line depreciation. For tax, Hong Kong has specific depreciation allowance rules for fixed assets that may differ in method and rates. File tax per the Inland Revenue Department's rules; consult an accountant for complex cases.
How does straight-line differ from declining-balance?
Straight-line (used here) assumes even wear, fixed annual charge — simple and smooth, good for stable assets (buildings, furniture). Declining-balance charges a fixed rate on the reducing book value, front-loading depreciation — better for assets that lose value early (electronics, vehicles). Sum-of-years'-digits is another accelerated method. Total depreciable amount (cost - salvage) is the same; only the timing differs.
What if salvage value or life was estimated wrongly?
Both are estimates at inception that directly affect annual depreciation. If they prove materially off, accounting treats it as a change in estimate: from the change date, recompute future depreciation using the latest book value, remaining life and new salvage — without restating prior years. Estimates need not be perfect but should be reasonable and reviewed. Permanent impairment needs a separate impairment test.
相關工具
參考資料
內容審核：香港計算器財經團隊。計算邏輯與公式參考香港金融管理局（HKMA）及投資者及理財教育委員會（IFEC）之個人理財計算指引，結果僅供參考，實際以相關機構公佈為準。