Percentage Fee vs Fixed Fee Calculator NZ 2026
Rates current for the 2026/27 tax year. Reviewed 5 August 2026.
Accounting for a sole trader is sold two ways. A traditional firm quotes a fixed annual fee for a defined piece of work, usually the return and some advice. A percentage service charges a share of what you earn, often with an annual cap, and typically bundles tax payments, filing and expense handling into the same price. Comparing them by headline number is close to meaningless, because one moves with your income and the other does not, so which is cheaper depends entirely on what you earn. There is always exactly one income at which they cost the same, and knowing where that point sits relative to your own earnings answers the question immediately. Two further things change the real cost and are almost never shown on a price page. If you are GST registered you reclaim the GST, so the advertised percentage is the true cost; if you are below the registration threshold you cannot, and the fee is effectively 15 percent higher than advertised. Both fees are also ordinarily deductible, so a third of the cost comes back through a lower tax bill for anyone in the 33 percent band. This calculator handles all four effects, on whatever numbers you enter.
What each option actually costs
How the two compare across incomes
Costs before tax. The percentage option rises with income until the cap binds, after which it is flat and its effective rate falls.
| Income | Percentage fee | Effective rate | Fixed fee | Cheaper |
|---|
Why the crossover is the only number that matters
A fixed fee divided by a percentage rate gives the income at which the two are equal. At 1 percent against a $2,000 fee that is $200,000, and the arithmetic is that simple whenever there is no cap. Below that income the percentage costs less, above it more. It is worth calculating rather than assuming, because people consistently misjudge it: 1 percent sounds small and $2,000 sounds large, so the fixed fee feels expensive at every income when in fact it is the cheaper option for anyone earning above the crossover.
What a cap does to the curve
A cap stops the percentage growing, which changes the shape of the comparison entirely. Below the cap the percentage behaves normally. At the cap it becomes a fixed fee, and from there its effective rate falls continuously as income rises: a $1,500 cap is 1 percent at $150,000, 0.75 percent at $200,000 and 0.5 percent at $300,000. The consequence is that a capped percentage fee can beat a fixed fee at both ends of the income range while losing in the middle, so a single crossover point is no longer the whole story and the table above is worth reading.
Worked example
A GST-registered sole trader earns $100,000 and is comparing a 1% service capped at $1,500 against a fixed quote of $2,000. The percentage fee is $1,000.00, well below the cap, so the percentage option is $1,000.00 cheaper before tax. Because they are registered, the GST on both fees is reclaimed and neither headline changes. Both fees are deductible, and at a 33% marginal rate the deduction returns $330.00 of the percentage fee and $660.00 of the fixed one, so after tax they cost $670.00 and $1,340.00. The gap narrows to $670.00, because a deduction shrinks the larger cost by more.
Without the cap the two would cross at $200,000 of income, but the cap binds first at $150,000. Above that point the percentage fee never exceeds $1,500, so it stays cheaper than the $2,000 quote at every income above the cap as well. With these particular numbers the fixed fee never wins, which is exactly the sort of conclusion a headline comparison hides.
How this is calculated
The percentage fee is your income multiplied by the rate, limited to the cap if one is entered. If you are not GST registered, both fees are increased by 15 percent because the GST cannot be reclaimed. The deduction saving is each fee multiplied by your marginal tax rate, and the after-tax cost is the fee less that saving. The break-even income is the fixed fee divided by the percentage rate, which is the income at which the two are equal; if a cap is in force and the capped fee never reaches the fixed fee, no crossover exists and the table shows the percentage option winning throughout. The cap binding point is the cap divided by the percentage rate.
Related NZ calculators
- Irregular Income Tax Smoothing Calculator for what to reserve from lumpy income
- Salary Plus Self-Employed Tax Calculator if you also have a job
- Self-Employed Take-Home Calculator for what you keep after tax and ACC
- GST Registration Threshold Calculator for whether you should be registered
- Hourly Rate Calculator for the rate that covers costs like these