Self-Employed Emergency Fund Calculator NZ 2026

Reviewed 7 August 2026.

Quick answer With $4,200 of fixed monthly costs and a worst month of $2,600, a bad month leaves you $1,600.00 short. Covering six of those needs $9,600.00, and the $7,500.00 of tax you have reserved but not yet paid sits on top of it, so the buffer to hold is $17,100.00. Against $12,000 saved that is a shortfall of $5,100.00.
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The advice to keep three to six months of expenses was written for people on a salary, where income either arrives in full or stops completely, and it translates badly to self-employment. Self-employed income rarely goes to zero. It sags: a quiet month, a client who goes elsewhere, a season that does not arrive. What you need to survive is not your whole cost base but the gap between what still comes in and what still goes out, and that gap is specific to you. There is also a second layer that employees never deal with. Tax on income you have already earned is money in your account that is not yours, and a buffer that quietly includes it is not a buffer at all. This calculator sizes the fund from your own worst month rather than a rule, keeps the tax layer separate so it cannot be spent twice, and shows how long what you already hold would genuinely last.

Buffer to hold
$17,100.00
including $7,500.00 of tax not yet paid
Shortfall against it
$5,100.00
still to save
What you hold covers
2.8
months of a bad run, after tax is set aside

How the buffer is built

Personal costs a month$3,400.00
Business costs a month$800.00
Fixed outgoings a month$4,200.00
Income in your worst month$2,600.00
Monthly gap to cover$1,600.00
Months of cover wanted6
Income buffer needed$9,600.00
Tax reserved but not yet paid$7,500.00
Total to hold$17,100.00
Currently saved$12,000.00
Genuinely available after tax is set aside$4,500.00
A bad month against your average60.00%

What the generic rule would have told you

The same situation sized three ways, so you can see how far the rule of thumb is from your actual exposure.

MethodBufferAgainst yours
This is an estimate. It assumes a bad run looks like your worst recent month repeated, which is a reasonable planning assumption and not a forecast. It does not model losing your largest client entirely, a health event, or a provisional tax instalment landing in the same quarter as the downturn. If your income comes mostly from one client, size the gap on losing that client rather than on your historic worst month.

The gap, not the whole cost base

The number that matters is not what you spend, it is what you spend minus what still arrives when things are bad. A contractor whose quiet months still bring in two thirds of their costs needs a far smaller buffer than the rule of thumb suggests, and telling them to save six months of total expenses is asking them to hold money that will never be needed. The opposite case is more dangerous. Someone whose income can genuinely stop, because it comes from one client or one season, needs the full cost base covered and the rule of thumb is not conservative at all. Using your own worst month rather than a general figure is what separates those two situations.

Tax is not savings

This is the single most common way a self-employed person gets caught out. Money reserved for income tax and ACC on work already done sits in your bank account looking exactly like savings, and for months at a time nothing forces the distinction. Then a terminal tax date and a quiet quarter arrive together, the buffer turns out to have been the tax money all along, and what looked like a healthy position becomes a payment arrangement with Inland Revenue. Keeping the two apart, ideally in separate accounts, costs nothing and removes the failure mode entirely.

Sizing the cover period honestly

How many months to cover is a judgement about your own market rather than a financial calculation. Work that is won in weeks and lost in weeks needs less cover than work with long sales cycles, because recovery is faster. The questions worth asking are how long it took you to replace income the last time you lost some, and whether that was luck. Six months is a reasonable default for most contracting, three is defensible if your pipeline is genuinely short and diverse, and twelve is not paranoid for seasonal or project work where a missed season cannot be made up.

Worked example

A sole trader has $3,400.00 of personal costs and $800.00 of business costs each month, so $4,200.00 goes out regardless. Their worst month in the last year brought in $2,600.00, against an average of $6,500.00, so a bad month is a 60.00% drop and leaves a gap of $1,600.00.

Covering 6 such months needs $9,600.00. They also hold $7,500.00 of tax reserved against income already earned, which is not theirs to spend, so the total to hold is $17,100.00. They have $12,000.00 saved, of which only $4,500.00 is genuinely available once the tax is set aside, leaving a shortfall of $5,100.00. That available money covers 2.8 months of a bad run rather than the six they were aiming for.

How this is calculated

Fixed outgoings are personal costs plus business costs. The monthly gap is fixed outgoings less your worst month of income, floored at zero, since a worst month that still covers everything needs no income buffer. The income buffer is that gap multiplied by the months of cover you chose. Tax reserved but not yet paid is added on top rather than blended in, because it is a liability rather than a reserve. Genuinely available savings is what you hold less that tax. Months covered is the available figure divided by the monthly gap. The comparison table applies the conventional three and six month rules to your total fixed outgoings, which is how those rules are normally stated.

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Frequently asked questions

How much emergency fund does a self-employed person in New Zealand need?

More than an employee, and the right amount depends on your own income pattern rather than a rule. The useful measure is the gap between your fixed costs and your worst realistic month, multiplied by how long a bad run might last, plus any tax you have collected but not yet paid. For steady contracting that can be less than three months of expenses; for lumpy project work it is often more than six.

Why does the three to six months rule not work for the self-employed?

Because it was written for employees, whose income either arrives in full or stops entirely. Self-employed income rarely goes to zero; it sags. A rule based on total expenses over-saves for someone whose worst month still covers half their costs, and under-saves for someone facing a provisional tax instalment in the same quarter.

Should tax money count as part of my emergency fund?

No. Tax you have reserved against income already earned belongs to Inland Revenue and is simply sitting in your account until the due date. Counting it as a buffer is the most common reason a self-employed person appears to have savings and then cannot pay a tax bill. This calculator treats it as a separate layer on top of the buffer.

Where should a self-employed emergency fund be held?

Somewhere you can reach within a day or two and cannot spend by accident, which usually means a separate on-call account rather than a term deposit or the account your card is attached to. The return matters far less than the availability: a buffer that is locked up for 90 days is not a buffer.

Does ACC cover me if I cannot work?

ACC covers injury, not illness and not a shortage of work, and payments are based on your past earnings rather than your current commitments. It also does not start immediately. An emergency fund covers the cases ACC does not, which are the more common ones.