Medical Certificates For Casual Employees In New Zealand

Casual staff can be a huge help when you’re trying to cover busy periods, seasonal spikes, or last-minute shifts.

But when a casual employee calls in sick (or says they’re unfit for work), it’s common for small business owners to wonder: can we ask for a medical certificate, and when?

This guide breaks down the rules in plain English, with a focus on what you can (and can’t) do as an employer. We’ll also cover how sick leave works for casual employees, what to put in your policies, and how to manage medical information without creating privacy issues. This article is general information only and isn’t legal advice for your specific situation.

If you’re trying to understand the rules around medical certificates for casual employees in New Zealand, you’re in the right place.

Are Casual Employees Entitled To Sick Leave In New Zealand?

Yes, many casual employees in New Zealand can be entitled to sick leave - but it depends on whether they meet the eligibility requirements under the Holidays Act 2003.

In practice, the confusion usually comes from the word “casual”. Some people use it to mean “irregular shifts”, but legally, what matters is whether the person is your employee and whether they meet the statutory thresholds for leave.

When Does Sick Leave Start For Casual Employees?

Under the Holidays Act 2003, employees generally become entitled to paid sick leave after:

• 6 months of current continuous employment with you; or
• They have worked for you for 6 months and, during that period, have worked at least an average of 10 hours per week and at least 1 hour per week or 40 hours per month (this second pathway often catches casual employees who work regularly).

Once eligible, an employee is entitled to a minimum number of paid sick leave days per year (and this minimum can change over time depending on legislation). Many employers provide more than the minimum in their employment agreement or policies, but you can’t provide less.

If you’re unsure how to define “casual” properly (and what entitlements flow from that), it’s worth getting clarity early - it’s much easier than untangling issues later. A well-drafted Employment Contract is usually the starting point.

What If The Casual Employee Isn’t Eligible Yet?

If the casual employee isn’t eligible for paid sick leave yet, that doesn’t mean you can’t ask for evidence in some situations - but the “sick leave” framework (including evidence requirements) is usually the context where these questions come up.

Also keep in mind:

• Even if the employee isn’t entitled to paid sick leave, you still have health and safety obligations not to require someone to work if they’re not fit for work (especially in roles involving food, vulnerable people, safety-critical tasks, or heavy machinery).
• Your approach should be consistent and not discriminatory. If you treat one person harshly because of a health issue, that can create legal risk.

When Can You Ask A Casual Employee For A Medical Certificate?

This is the core question for most employers searching for medical certificates for casual employees in New Zealand.

In New Zealand, employers can generally require the employee to provide “proof” of sickness or injury (often a medical certificate) if the employee has been sick or injured for 3 or more consecutive calendar days.

Those are calendar days, not rostered working days. So weekends and non-working days can still count towards the “3 consecutive days”.

Can You Ask For A Medical Certificate Earlier Than 3 Days?

Yes - but only if you cover the cost.

As an employer, you can request proof (including a medical certificate) within the first 3 consecutive calendar days if you:

• tell the employee as early as possible that you require it; and
• agree to pay the reasonable costs of getting the medical certificate.

In a small business, “reasonable costs” usually means the typical fee charged by a medical clinic for issuing a certificate. If you’re going to require early evidence, it’s a good idea to set expectations upfront (and budget for it where needed), rather than trying to negotiate it in the moment.

Does This Apply To Casual Employees Too?

If the person is your employee and is taking sick leave (or requesting paid sick leave), these rules apply regardless of whether they’re full-time, part-time, or casual.

The tricky part is that casual employees often have irregular work patterns - so it helps to separate two questions: (1) whether the employee has been sick or injured for 3 consecutive calendar days, and (2) which rostered shifts (if any) fall within that period.

Example: if a casual employee is rostered for Monday and Tuesday and calls in sick, then remains unwell on Wednesday (even if they weren’t rostered), that can still be “3 consecutive calendar days”. But whether you ask for proof, and what leave is paid, will usually relate to the rostered days the employee would otherwise have worked.

What Counts As An Acceptable Medical Certificate (And What You Shouldn’t Ask For)

Most employers just want a straightforward note confirming the employee was unfit for work for a particular period.

That’s usually all you should be requesting.

What A Medical Certificate Typically Includes

A standard medical certificate commonly confirms things like:

• the employee was assessed by a health practitioner;
• the employee is (or was) unfit for work for a set period;
• any recommended restrictions (e.g. “light duties only” or “no lifting”); and
• the date of assessment and the provider’s details.

In many cases, you don’t need the diagnosis or detailed medical background - and trying to push for it can create privacy and employment law issues.

Be Careful With Requests For “More Detail”

Even when you’re frustrated about repeated absences or last-minute cancellations, it’s important not to cross the line into requesting information you don’t need.

As a general rule, you should avoid asking for:

• the underlying diagnosis (unless there’s a genuine reason related to safety or accommodations);
• details of medications; or
• information about unrelated medical history.

If you do need additional information (for example, to assess whether the employee can safely perform certain tasks), you should approach this carefully and proportionately - and ideally with legal advice.

This is also where having strong employment documentation matters. A properly drafted Employment Contract and clear policies can help you request evidence in a consistent, fair way.

How To Handle Medical Information Without Breaching Privacy

Medical information is sensitive personal information. That means it needs to be handled with extra care.

Even if you’re a small business, you still need to comply with the Privacy Act 2020 when you collect, store, use, or disclose employee medical information.

Practical Privacy Steps For Employers

Here are simple (but important) steps to reduce risk:

• Only collect what you need to manage the employment relationship and leave entitlements.
• Store medical certificates securely (not in a public folder, shared drive, or on an open counter).
• Limit access to those who genuinely need to know (often just the owner/manager and payroll).
• Don’t gossip about an employee’s health, even informally.
• Have a retention approach (keep employment records appropriately, but don’t keep sensitive documents longer than necessary).

If your business collects and manages personal information across the board (employees, customers, website visitors), having a tailored Privacy Policy and internal privacy processes is a smart move, especially as your team grows.

What If The Employee Refuses To Provide A Medical Certificate?

If you’ve made a lawful request for proof and the employee refuses (or can’t provide it), you may be entitled to treat the absence as unauthorised or decline payment for sick leave - but you should tread carefully.

Before taking any disciplinary action, consider:

• Was your request lawful (3+ consecutive days, or you’re paying the costs for an earlier request)?
• Did you communicate the requirement clearly and early?
• Is there a reasonable explanation (e.g. access issues, inability to get an appointment quickly)?
• Have you applied your approach consistently across staff?

Disciplinary or performance steps should follow a fair process. If you’re considering formal action, it’s worth getting advice before you move - small missteps in process can create bigger problems than the original absence.

Common Scenarios For Small Businesses (And How To Manage Them)

When you’re running a small team, absence management can feel personal - especially if one sick call-out means you’re the one stepping onto the floor.

Here are a few common scenarios and what you can do.

Scenario 1: “They’re Casual, So They Don’t Need A Medical Certificate… Right?”

Not quite. If they’re an employee and the sick leave evidence rules apply (including because they’re eligible for paid sick leave), you can require proof within the usual framework.

The better question is whether your casual employee has become eligible for sick leave under the Holidays Act - which often happens earlier than employers expect, particularly if the “casual” worker is actually working most weeks.

Scenario 2: Frequent One-Day Sick Absences On Busy Days

This can be tough. The law doesn’t automatically let you demand a medical certificate for a single day - unless you request proof within the first 3 consecutive days and you pay the reasonable cost of obtaining it.

If you’re noticing a pattern, consider:

• setting a consistent policy for when you will request early evidence (and budgeting to pay for it);
• having a non-accusatory conversation with the employee about what’s going on; and
• checking your rostering and engagement approach (sometimes “casual” staff feel pressure to accept shifts even when they’re not reliably available).

If a pattern raises concerns about honesty, that becomes an employment relationship and process issue - not just a paperwork issue.

Scenario 3: The Medical Certificate Says “Unfit For Work”, But You Think They Could Do Light Duties

It’s risky to override medical advice based on a gut feeling.

If the certificate doesn’t address modified duties but you think light duties could be an option, you can ask the employee (politely) whether they can obtain clarification from their medical provider about what they can do.

But be careful: you should not pressure the employee to return before they’re fit, and you should ensure any work they do is safe. Your obligations under the Health and Safety at Work Act 2015 mean you must take reasonably practicable steps to keep workers safe.

Scenario 4: The Employee Texts “Sick” Five Minutes Before Their Shift

In a small business, this happens - and it can be disruptive.

Your best protection is to set expectations upfront around notification, including:

• how early staff should notify you if they can’t attend;
• who they should contact (and by what method);
• what information they need to provide (e.g. “unwell and unable to work today”); and
• when medical certificates (or other proof) may be required.

These expectations should align with the employment agreement and your internal policies.

How To Put A Clear Process In Place (Without Scaring Off Casual Staff)

Most casual employees aren’t trying to game the system - they just want clear instructions and fair treatment.

A simple, consistent approach can protect your business while keeping a good working culture.

Set Expectations In Writing

To manage medical certificates properly, make sure your documents cover:

• sick leave eligibility (including how it works for casual staff who become eligible over time);
• notification requirements (when and how employees should let you know);
• when you may request proof (including the 3-day rule and early requests where you pay costs);
• privacy handling (how medical information is stored and who can access it); and
• consequences of failing to provide evidence where lawfully required (handled through a fair process).

If you haven’t reviewed your documentation in a while, it may be a good time to do a quick legal check-up - especially if you’re scaling up, changing rosters, or relying more heavily on casual staff.

Train Your Managers (Or Whoever Does The Rostering)

In small businesses, the “manager” might be you, a supervisor, or whoever is on duty when a text comes through.

Make sure whoever handles absences understands:

• the difference between “asking for details” and “asking for evidence”;
• when you must pay for the certificate (early request);
• how to communicate consistently; and
• how to avoid privacy slip-ups.

Keep Records (But Don’t Over-Collect)

Good record-keeping helps if you later need to confirm sick leave balances, show consistency, or respond to a dispute.

At the same time, don’t turn this into a bigger data-collection exercise than it needs to be. You’re usually just verifying that the employee was unfit for work for a particular period.

Key Takeaways

• Many casual employees can become entitled to paid sick leave under the Holidays Act 2003 once they meet eligibility thresholds, even if their shifts are irregular.
• You can usually require proof (often a medical certificate) once an employee has been sick or injured for 3 or more consecutive calendar days, and “calendar days” can include weekends and non-working days.
• You can ask for proof earlier than 3 days, but you generally need to request it as early as possible and pay the reasonable cost of obtaining a medical certificate if that’s what you require.
• Medical certificates should be used to confirm fitness for work - you should avoid asking for unnecessary medical details, as this can create legal and privacy risk.
• Medical information is sensitive personal information, so store it securely, limit access, and handle it in line with the Privacy Act 2020.
• The best way to prevent disputes is a consistent process: clear written expectations, staff training, and fair handling of absences and evidence requests.

If you’d like help tightening up your approach to sick leave, medical certificates, and casual staff management, you can reach us at 0800 002 184 or team@sprintlaw.co.nz for a free, no-obligations chat.