Asset depreciation and Investment Boost calculator
Claim deductions with confidence
Bought new equipment, tech, or furniture for your business? If the asset costs more than $1,000, you can’t write it off in one go. Instead, you claim the cost gradually through depreciation. And if the asset was first available for use on or after 22 May 2025, you may also be able to claim an upfront 20% deduction through the government’s Investment Boost.
Getting the numbers right means choosing the correct depreciation method, applying the right IRD rate, and pro-rating for the number of months you’ve actually used the asset. This calculator handles all of that and shows you how your claim plays out over five years.
How your claim is calculated
Understanding the logic behind the numbers will help you enter the right inputs and trust the result you get.
Asset cost and purchase date.
Enter the GST-exclusive price of the asset and the date it was first available for use. The calculator uses the purchase date to work out how many months fall within the current income year (assuming a 31 March balance date), since first-year depreciation is pro-rated rather than claimed in full.
New asset status.
Use the dropdown to confirm whether the asset is brand new. Only new assets first available for use on or after 22 May 2025 qualify for the 20% Investment Boost. If you select No, the calculator skips the boost and applies standard depreciation only.
Depreciation method: DV or SL.
The IRD allows two methods. Diminishing Value (DV) claims a percentage of the asset's remaining book value each year, meaning larger deductions early on that taper off over time. Straight Line (SL) claims a fixed percentage of the original cost base each year, spreading the deduction more evenly. Your accountant can help you decide which suits your situation, though DV is more commonly used for most business assets.
IRD depreciation rate.
Enter the rate that applies to your asset category. This varies by asset type, for example, laptops are typically 50% (DV) or 40% (SL), while office furniture rates vary depending on the specific item. You can look up your asset's rate on the IRD's depreciation rate finder. The calculator applies this rate to your depreciable base (the 80% remaining after the Investment Boost, or the full cost if the boost doesn't apply).
The 5-year outlook.
The calculator generates a year-by-year table showing your opening value, annual depreciation claim, and closing book value for each of the next five years. This helps you see how the asset's tax value drops over time and plan for future upgrades or replacements.
See how the Investment Boost changes your first-year claim
A business owner buys a $15,000 piece of equipment in March 2026. It’s a new asset, so the 20% Investment Boost applies. They use the Straight Line method at 30%.
With the Investment Boost:
| Investment Boost (20% of $15,000) | $3,000 |
| Depreciable base ($15,000 − $3,000) | $12,000 |
| Year 1 depreciation ($12,000 × 30% × 1/12 months) | $300 |
| Total Year 1 claim | $3,300 |
Without the Investment Boost:
| Depreciable base | $15,000 |
| Year 1 depreciation ($15,000 × 30% × 1/12 months) | $375 |
| Total Year 1 claim | $375 |
One more thing to keep in mind
Depreciation rates vary significantly between asset types, and using the wrong rate is one of the most common mistakes. The IRD’s depreciation rate finder is the best place to confirm the correct rate for your specific asset before entering it into the calculator.
Want the full picture?
Our guide to claiming the 20% NZ Investment Boost for business assets explains how these rules work across different asset types and business structures.
Tax time putting pressure on cash flow?
A solid claim reduces your tax bill, but tax season can still hit at the worst time for cash flow. If you need to bridge a gap, we can help with fast, flexible funding built for small businesses.
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FAQs
Common questions answered
Generally, no. You typically only need to maintain one for a continuous 90-day period. That logbook then establishes your business-use percentage for up to three years, provided your driving habits stay broadly the same.
Driving between job sites, heading to client meetings, and picking up supplies all count. Your daily commute to a regular place of work generally doesn’t, even if you’re self-employed.
- If your employer already reimburses you at or above the IRD rates, there’s generally nothing further to claim. If they reimburse at a lower rate, you may be able to claim the shortfall. This is one where a conversation with your tax agent is worth having.
