Business Surplus Cash Calculator NZ 2026/27
Surplus cash sitting in a business transaction account is one of the most common and least examined leaks in a small company's finances, largely because nothing appears to be going wrong. The balance is not falling, no fee is being charged, and the money is exactly where it is most convenient. What is missing is the interest it could be earning, and at current deposit rates that gap runs to thousands of dollars a year on quite ordinary balances. Fixing it requires answering two separate questions rather than one. The first is how much of the balance is genuinely spare, because a cash buffer is not idle money, it is what keeps a business solvent through a slow quarter or a client who pays late, and committing it to a fixed term to earn a little more is a poor trade. The second question is where the rest should sit, and here companies face a tax position that differs from an individual's in a way that catches people out. Inland Revenue treats a New Zealand resident company as a zero-rated investor in a portfolio investment entity, with the income flowing into the company return to be taxed at the ordinary company rate. The consequence is that the prescribed investor rate advantage which makes PIE funds attractive to higher-earning individuals produces nothing for a company, so the choice comes down to rate, term and access rather than tax structure.
PIE treatment for companies, confirmed against Inland Revenue guidance: a company resident in New Zealand is a zero-rated investor and should use a PIR of 0%, and all income or loss from a multi-rate PIE must be included in the company tax return. Dividends or distributions received from a multi-rate PIE are not included in that return.
The consequence is that a company's after-tax return is the same whether income arrives as bank interest or through a PIE, so the comparison here is driven by gross rate, term and access rather than by structure.
The individual comparison uses the top prescribed investor rate of 28% against marginal rates of 30%, 33% and 39%, which is where the PIE advantage comes from for individuals.
Buffer is monthly operating costs multiplied by the months of cover you choose. Surplus is the balance beyond it, floored at zero.
Excluded: resident withholding tax timing, which affects cash flow rather than the final liability; provisional tax and GST obligations, which should be treated as committed rather than surplus; break costs on early term deposit withdrawal; and any imputation or dividend consequences of distributing rather than retaining.
Not financial, tax or investment advice. Last verified: .
After-tax return by option
| Where it sits | Gross rate | After 28% tax | On the surplus | On the whole balance |
|---|---|---|---|---|
| Business transaction account | 0.10% | 0.07% | $46.80 | $144.00 |
| On-call business savings | 2.50% | 1.80% | $1,170.00 | $3,600.00 |
| 6-month term deposit | 3.40% | 2.45% | $1,591.20 | $4,896.00 |
| 12-month term deposit | 3.60% | 2.59% | $1,684.80 | $5,184.00 |
The whole-balance column is illustrative only. Committing your operating buffer to a fixed term is exactly the trade this page advises against.
Why a company gets no PIE advantage
| Investor | Rate on interest | Net from bank interest | Net through a PIE | PIE advantage |
|---|---|---|---|---|
| A company | 28.00% | 2.88% | 2.88% | 0.00% |
| Individual on 39% | 39.00% | 2.44% | 2.88% | 0.44% |
| Individual on 33% | 33.00% | 2.68% | 2.88% | 0.20% |
| Individual on 30% | 30.00% | 2.80% | 2.88% | 0.08% |
Shown on a 4.00% gross return. The PIE advantage exists only where the investor's own rate is above the top PIR of 28%, and a company's is not.
How the buffer choice changes what is available
| Months of cover | Buffer held | Surplus available | Surplus earning 3.60% |
|---|---|---|---|
| 1 month | $45,000.00 | $155,000.00 | $4,017.60 |
| 2 months | $90,000.00 | $110,000.00 | $2,851.20 |
| 3 months | $135,000.00 | $65,000.00 | $1,684.80 |
| 6 months | $270,000.00 | $0.00 | $0.00 |
A larger buffer costs real income, which is the honest trade. It is usually still the right call, because running out of cash ends a business and earning less interest does not.
A Company Is A Zero-Rated PIE Investor
This is the fact that most often surprises business owners who invest personally, and it is worth stating precisely.
Inland Revenue's position is that a company resident in New Zealand is a zero-rated investor and should use a PIR of 0%, and that all income or loss from a multi-rate PIE must be included in the company tax return.
So the PIE does not tax the income on the way through. It arrives in the company return and is taxed at 28%, exactly as bank interest would be. On a 4.00% return the company nets 2.88% either way, and the advantage is 0.00.
Where That Advantage Comes From For Individuals
The PIE benefit is a rate benefit, and it only appears when the investor's own rate exceeds the top prescribed investor rate of 28%.
An individual on a 39% marginal rate nets 2.44% from bank interest and 2.88% through a PIE, a gain of 0.44 points. On a 33% rate the gain narrows to 0.20 points, and on 30% to 0.08.
A company sits at 28%, which is the PIR itself, so there is no gap to capture. The structure that helps a shareholder personally does nothing for their company. Our PIE savings vs bank savings calculator works that comparison for an individual.
Worked Example: $200,000 In The Business
Buffer: three months at $45,000.00 a month is $135,000.00, which stays on call.
Surplus: $65,000.00 can be committed to a term.
Currently earning: $144.00 a year after tax, with everything in a transaction account at 0.10%.
If the whole balance earned 3.60%: $5,184.00 after tax, a difference of $5,040.00.
Even moving only the genuine surplus to a 12-month deposit adds $1,684.80 a year, on money that was doing nothing.
The Buffer Is Not The Place To Optimise
The temptation once the numbers are visible is to shrink the buffer, since a smaller buffer produces more investable surplus.
Dropping from three months to one lifts the surplus from $65,000.00 to $155,000.00 and the income from $1,684.80 to $4,017.60. That is a real gain and it is usually the wrong trade.
Running out of cash ends a business. Earning less interest does not. The buffer is insurance, and the extra income is the premium you are choosing not to collect. Our business cash buffer calculator works the sizing question properly.
Match The Term To What You Actually Know
The practical risk with term deposits is not the bank failing, it is needing the money before maturity.
Breaking a deposit early usually forfeits most of the additional interest, which can leave you behind an on-call account that was available the whole time. The extra return over on-call is often 1.10 points, so a break in the wrong month erases a year of the advantage.
Splitting a larger surplus across several maturity dates means only part of it is locked at any moment, which preserves most of the rate while restoring some access. Our term deposit ladder calculator sets that up, and our term deposit break cost calculator prices what an early exit would actually cost.
The Question Underneath
Optimising where company cash sits is worth doing, and it is a smaller question than whether the cash should be in the company at all.
Retaining surplus defers the shareholder's tax rather than avoiding it. Company profits taxed at 28% carry imputation credits, and a shareholder on a higher marginal rate tops up the difference when a dividend is eventually paid, so the eventual rate is the shareholder's rather than the company's.
Whether to retain, distribute, or use the money in the business turns on the shareholders' circumstances rather than the company's, and it is a conversation for your accountant rather than a calculator. Our true cost of employee calculator and business cash buffer calculator cover the operational side.
Related NZ Business Calculators
- Business Cash Buffer Calculator: sizing the reserve properly.
- PIE Savings vs Bank Savings Calculator: the same comparison for an individual.
- Term Deposit Ladder Calculator: keeping access while holding the rate.
- True Cost Of Employee Calculator: the other side of a business budget.
- Emergency Fund Placement Calculator: the personal version of the buffer question.