Medical Certificates and Proof of Sickness

Managing sick leave is one of those parts of running a business that sounds simple in theory, but gets complicated quickly in real life.

You want to support your team when they’re unwell. At the same time, you still need to keep shifts covered, keep customers happy, and make sure you’re treating everyone fairly and consistently.

That’s where questions about medical certificates often come in: when can you ask for one, what counts as “proof of sickness”, who pays for it, and what should you do if an employee can’t (or won’t) provide it?

Below, we’ll break down the key rules in New Zealand, what “proof” actually means in practice, and how to handle common scenarios as a small business employer.

What Is A Medical Certificate (And What Counts As “Proof Of Sickness”)?

A medical certificate (sometimes called a doctor’s certificate) is one common way an employee can show they were not fit for work.

In employment law, you’ll usually see the broader term “proof of sickness or injury”. Importantly, proof doesn’t always have to be a standard GP certificate - but if you choose to require proof under the legal rules (rather than simply accepting the absence), you can generally ask for proof from a registered medical practitioner. In practice, many employers will accept other supporting information by agreement where it’s appropriate and reliable (for example, where access to a GP is genuinely difficult), but you should be consistent and careful about what you accept.

From a practical employer perspective, your goal isn’t to “catch people out”. It’s to:

confirm the absence is legitimate when you’re entitled to ask for proof,
keep payroll and leave records accurate, and
make decisions (like rostering and cover) based on reliable information.

Because this can quickly become sensitive, it helps to treat medical certificates as part of your broader employment compliance framework (the same way you’d treat timekeeping, performance management, and privacy).

Why The “Proof” Requirement Matters For Small Businesses

If you run a lean team, one person away can have a big impact.

Clear rules about medical certificates protect you in a few ways:

Consistency: you avoid treating employees differently (which can create conflict or legal risk).
Budget control: you understand when you may need to cover the cost of proof.
Better planning: you can make earlier calls on shift cover and operational changes.

The key is knowing what the law allows, and then building a fair process around it.

When Can You Ask For A Medical Certificate In NZ?

In New Zealand, employers can ask for proof of sickness or injury in certain circumstances. The rule most employers know is the “three days” idea: if someone is sick for three or more consecutive calendar days, you can require proof.

But there’s another situation that often gets missed: you can also ask for proof within the first three days if you do it correctly.

Scenario 1: The Employee Is Off Sick For 3+ Consecutive Days

If an employee is away for three or more consecutive calendar days due to sickness or injury, you can require them to provide proof.

“Consecutive calendar days” includes days the employee wouldn’t normally work (like weekends) if they fall within the period of illness. For example, if someone is sick Friday and Monday, that can still be considered a consecutive period that spans the weekend.

In this scenario, you can generally require the proof at the employee’s cost (unless your employment agreement says otherwise).

Scenario 2: You Ask For Proof Within The First 3 Days

You can ask for a medical certificate (or other proof of sickness) even within the first three days, but there’s a catch:

you must tell the employee as early as possible that you require proof, and
you must pay the reasonable cost of getting that proof.

This option can be useful where you have genuine operational pressures (for example, you run a small hospitality venue and a key staff member calls in sick right before a busy weekend), or where there’s a pattern of absences that you need to manage fairly.

The best approach is to apply this rule consistently and carefully, rather than only using it for certain employees (which can look like unfair targeting).

Put It In Writing (So Everyone Knows The Rules)

Even though these rules come from legislation, you’ll usually want to reflect your approach in your employment documentation so your team understands the process from day one.

For example, your Employment Contract can set out expectations around notification, proof requirements, and how sick leave is recorded.

Who Pays For The Medical Certificate (And What Is A “Reasonable Cost”)?

Cost is one of the biggest practical issues for small business employers.

The general position in New Zealand is:

If the employee has been sick for 3 or more consecutive calendar days and you request proof, the employee usually pays.
If you request proof within the first 3 days, you must pay the reasonable cost.

“Reasonable cost” isn’t always a fixed number, because fees can vary depending on the clinic, the time, and what services are required. But as a rule of thumb, you should expect to cover the typical charge for obtaining a medical certificate from a GP or appropriate provider.

If you’re paying, you’ll also want to think about process:

Will the employee pay upfront and you reimburse them?
Do you want them to attend a particular clinic?
Do you have a cap or policy setting out what you’ll reimburse?

If you’re considering directing an employee to a specific provider, be careful: it can raise trust and privacy concerns. Often, it’s better to focus on what proof you need, rather than who provides it (unless there’s a legitimate reason).

What If The Employee Can’t Get An Appointment?

This is increasingly common. If an employee can’t get a same-day or next-day appointment, it doesn’t automatically mean they’re being dishonest.

Practically, you might:

ask them to book the earliest available appointment,
consider whether you can accept alternative supporting information in the circumstances (noting you can still require medical proof where you’re legally entitled to), and
document your communications clearly.

What you want to avoid is turning the process into a “gotcha” that escalates conflict.

How Much Information Can You Ask For (And What About Privacy)?

A common mistake is asking for too much detail.

As an employer, you usually only need confirmation that the employee is unfit for work for a stated period (or that they were seen and assessed). You generally don’t need their diagnosis or personal medical history.

Medical information is sensitive personal information, so you should treat it carefully and only collect what you genuinely need.

That’s why it’s smart to have clear internal privacy practices, especially if you store medical certificates digitally or share them with payroll, managers, or rostering staff. If your business collects and stores personal information, having a Privacy Policy in place is often part of building good compliance habits (even for smaller teams).

Practical Tips For Handling Medical Certificates Securely

Limit access: only people who need to know (e.g. payroll/HR) should see medical documents.
Store securely: avoid leaving certificates in open inboxes or shared drives without access controls.
Don’t overshare: managers often only need to know “off sick” and expected return date.
Keep good records: document requests for proof and reimbursements to show fairness and consistency.

Common Scenarios: What Should Employers Do In Practice?

Most problems around medical certificates aren’t about the rules themselves. They’re about how the conversation is handled when a real situation pops up.

Here are some common scenarios we see, and the practical steps that usually help.

An Employee Calls In Sick Often (Especially Before Or After Weekends)

If you notice a pattern, it’s reasonable to manage it.

Good steps include:

checking your records to make sure the pattern is real (not just a “feeling”),
having a calm conversation about attendance expectations, and
using the lawful medical certificate request rules consistently.

If the issue continues, you might need a more formal performance management approach. The key is to focus on attendance and operational impact, not accusations about whether someone is “really sick”.

An Employee Refuses To Provide A Medical Certificate

If you were entitled to ask for proof and the employee refuses without a good reason, you can generally treat the leave as not proven and decline to pay sick leave for that absence (or treat it as another form of leave by agreement). Depending on the wider context and your processes, refusal to follow a reasonable, lawful instruction may also become a conduct issue.

But tread carefully and keep things procedural:

confirm the request in writing (including the deadline and what you’ll reimburse, if applicable),
give the employee a reasonable opportunity to comply, and
ask if there’s any barrier (cost, access to a doctor, misunderstanding) you can resolve.

If the situation is escalating toward disciplinary action, it’s worth getting legal advice early. In employment law, process matters just as much as the underlying issue.

The Medical Certificate Looks “Vague” Or Doesn’t Say Much

Many certificates are brief by design (and for good privacy reasons). If the certificate confirms the employee is unfit for work for a certain period, that may be enough.

If you genuinely need clarity (for example, the employee is returning with restrictions, or you have health and safety concerns), you can ask follow-up questions that focus on capacity and safety rather than diagnosis.

This is where your health and safety duties may intersect with employment decisions. If you’re making changes to duties or hours, you should do it carefully and consult the employee. In some cases, employers also ask about adjusted hours or duties, which can overlap with issues like Reducing Staff Hours (and the legal risks if it’s not handled properly).

Mental Health And Stress Leave: Can You Ask For Proof?

Yes. Mental health-related absences can still be sick leave, and the same “proof of sickness” rules can apply.

Because it’s a sensitive topic, it’s important to:

avoid minimising the issue,
avoid asking for unnecessary medical detail, and
apply your policies consistently (so you don’t accidentally discriminate).

You may also want to think about your broader workplace culture and wellbeing approach. From a legal perspective, you still need to comply with the same sick leave and privacy principles when the illness is psychological rather than physical.

How To Set Up A Clear “Proof Of Sickness” Process In Your Business

If you want to avoid awkward, inconsistent decisions, the best time to set expectations is before anyone gets sick.

A simple, consistent process can save you a lot of time (and conflict) later.

1. Confirm Your Sick Leave Rules In Writing

At a minimum, your documentation should explain:

how employees should notify you (who to contact, by when, and how),
when you may request proof of sickness or injury,
timeframes for providing proof, and
how sick leave is recorded and paid.

For most small businesses, this starts with a properly drafted Employment Contract, and can be supported by policies in a staff handbook (especially as your team grows).

2. Train Your Managers (So They Don’t Accidentally Create Risk)

If you have supervisors or shift managers handling sick calls, make sure they know what to say (and what not to say).

A quick script helps, for example:

“Thanks for letting us know. Please keep us updated on when you expect to return.”
“Because of the length/timing of the absence, we’ll need proof of sickness. Let us know if you have any issues arranging that.”

What you want to avoid is managers pushing for personal medical details, or making comments that could be interpreted as bias or retaliation.

3. Apply The Rules Consistently (And Document Decisions)

Consistency is one of the biggest protections you have as an employer.

If you only request medical certificates from certain employees, you can unintentionally create arguments that you’re acting unfairly or targeting someone.

Documentation matters too. Keep a record of:

the absence dates,
when proof was requested,
whether you were requesting it within the first 3 days (and therefore paying), and
what was provided and when.

4. Be Careful When Absences Lead To Bigger Decisions

Sometimes a sick leave issue is really the start of something bigger: extended absence, inability to perform duties, or an employment relationship that’s breaking down.

If you’re moving toward termination, redundancy, or major changes, the legal risks increase significantly if you don’t follow a fair process. Getting advice early can help you avoid stepping into procedural mistakes that are expensive to fix later.

Depending on the situation, you may also need to review your notice and pay obligations, including Payment In Lieu Of Notice.

Key Takeaways

Medical certificates and other “proof of sickness” help you manage sick leave fairly, keep accurate records, and plan your staffing.
In New Zealand, you can generally require proof if an employee is sick for 3 or more consecutive calendar days, and the employee will usually pay the cost.
You can request proof within the first 3 days, but you must tell the employee as early as possible and pay the reasonable cost of obtaining it.
Be careful not to collect more medical information than you need, and make sure you store medical certificates securely to manage privacy risk.
If an employee won’t provide proof when you’re entitled to request it, you can usually decline to pay sick leave for that absence - but you should still follow a fair process and document everything.
Putting clear expectations in your employment documents and training managers on how to handle sick leave conversations can prevent disputes and protect your business.

If you’d like help setting up clear sick leave processes, reviewing your employment documents, or dealing with a tricky medical certificate situation, you can reach us at 0800 002 184 or team@sprintlaw.co.nz for a free, no-obligations chat.

Medical Certificates And Proof Of Sickness: Employer Rules In New Zealand