Loss Carry-Forward for NZ Traders: The Rule That Puts Money Back in Your Pocket

The short version

• NZ trading losses carry forward indefinitely — no time limit.
• A prior-year loss reduces your current-year taxable income before tax is worked out.
• You have to track and apply it yourself — IRD won't.
• Even a loss from 2018–19 can cut your 2025–26 bill.
• If you've had good years since a loss and never applied it, you've overpaid.

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Here's the one genuinely cheerful bit of NZ trading tax: a bad year doesn't only hurt once.

In New Zealand, trading losses carry forward with no expiry date and no cap. A loss from any earlier tax year can reduce your taxable income in a future profitable one. Most traders I talk to either don't know the rule exists, or they know but never tracked their losses well enough to use them — which means money left on the table every good year. Here's how it actually works.

What a carry-forward actually is

If your trading nets out to a loss in a tax year, that loss carries forward and reduces future taxable income. In NZ it sits under the general tax loss rules in the Income Tax Act — for someone in the business of trading, a net loss in a year becomes a tax loss that offsets future net income.

The key word is net. You don't carry forward individual bad trades — you carry forward the year's overall result, but only when it's negative.

How the maths works

It's a running ledger. Each year you:

1. Work out net trading P&L (all gains minus all losses)
2. Take off allowable expenses
3. If it's negative, record it as a carry-forward loss
4. If it's positive, subtract any prior carry-forward balance before calculating tax

Worked through:

• 2022–23: net −$12,000 → record $12,000 carried forward
• 2023–24: net profit $8,000 → apply $8,000, taxable trading income $0, $4,000 still carried forward
• 2024–25: net profit $19,000 → apply the remaining $4,000, taxable trading income $15,000, carry-forward now $0

In that run, $12,000 of losses shielded $12,000 of later profit from tax entirely. At a 30% marginal rate, that's $3,600 of tax legitimately not paid.

No time limit, really

This is the part that surprises people. Plenty of countries cap how long losses can be carried — five years, ten. NZ doesn't. A loss from 2015 can still be applied in 2026.

That matters if you had rough early years while you found your feet, took a break from trading, or never recorded losses that are now sitting there unused. If any of that's you, it's worth going back and working out what you've accumulated — every dollar of carry-forward is reducing a future bill.

Applying it on your IR3

The carry-forward goes into your net income calculation before you put trading income on the IR3 — it's not a separate line on the form. So:

1. Work out gross trading profit
2. Subtract deductible expenses
3. Subtract your prior carry-forward balance (up to the current year's profit)
4. Enter the result as your trading income

If an accountant files for you, hand them your carry-forward ledger. TradeLog NZ produces it automatically as part of the tax report.

What counts as a trading loss

The loss has to come from your trading activity. Net losses from forex, crypto, active share trading (where you're a business trader), CFDs or metals all qualify, and if you trade several instruments your combined net result across them decides whether you've got a carry-forward for the year.

What doesn't feed this particular carry-forward: rental property losses (own regime), capital losses from a genuinely passive portfolio (where you weren't trading as a business), or losses from an unrelated business.

Keeping the records

You need to be able to back up your carry-forward balance if IRD asks. That means your trade log for every loss year, the return or calculation showing the net loss, and a running ledger of the balance and how it's been applied. Seven years is the standard record-keeping period — but if a carry-forward originated more than seven years ago, keep those records anyway, because you're still carrying the loss and IRD can ask where it came from.

The trap: years you never applied it

This comes up more than you'd expect. Someone has a loss year in 2021–22, doesn't know about carry-forwards, and files the next three years without applying any offset. They've overpaid in each.

Can you fix it? Possibly — NZ generally lets you amend returns up to four years back. If the amounts are meaningful, it's worth asking an accountant whether an amended return stacks up. Going forward, just make sure any unused carry-forwards are factored into this year's return.

When you've also got a salary

Your carry-forward reduces your net trading income — it doesn't reach across and offset your salary directly. It applies within the trading activity first, before everything's combined.

Example: salary $70,000, gross trading profit $15,000, carry-forward $20,000. The carry-forward takes your trading income to zero this year, and the remaining $5,000 rolls to next year — you generally can't push trading income to −$5,000 and knock that off your salary. The interaction can get fiddly in edge cases, so if you're in one, confirm the treatment with your accountant.

A note on the Base Price Adjustment

If you're a non-cash-basis person under the financial arrangements rules — typically larger traders above the income/asset thresholds — a year-end Base Price Adjustment applies to open positions at 31 March, and it can throw off income or deductions that feed into the carry-forward. For most retail traders (cash basis persons), the BPA doesn't apply to open positions mid-arrangement; it happens when the trade closes. If you're not sure which you are, see the NZ forex tax guide or ask an accountant.

How TradeLog NZ handles it

TradeLog NZ keeps a running loss carry-forward ledger across every tax year. Finalise a year with a net loss and it's recorded; in later years the balance is applied in the calculation, and you can see exactly how much was used and what's left. The Pro tax report includes the ledger as a line item so your accountant sees both the prior loss and how it was applied this year. This is the kind of thing a manual spreadsheet quietly gets wrong over time — years get missed, the balance drifts — which is exactly the problem the automated ledger solves.

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Quick checklist

• Did you have net trading losses in any prior year?
• Have you recorded them and tracked the balance?
• Are you applying the carry-forward before working out this year's taxable income?
• Can you back up the balance with records?
• Missed applying it in earlier years? Is an amended return worth a look?

If you answered no to any of the first three, there's a real chance you're overpaying. Fix the ledger, apply it properly this year, and keep clean records from here.

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This is general information, not tax advice. Everyone's situation differs. Run your position past a qualified NZ accountant before filing. TradeLog NZ takes no responsibility for errors in your return.

IRD on tax losses | IRD loss carry-forward rules