KiwiSaver Provider Comparison for Weight Loss Surgery (2025 Guide)

When applying for a KiwiSaver withdrawal to help fund weight-loss surgery in New Zealand, your provider plays a huge role in how quickly and smoothly your application is approved.

Although all providers must comply with the KiwiSaver Act, each one interprets the medical and hardship criteria slightly differently. Some are stricter, some are faster, and some are more supportive for medical withdrawals, especially for bariatric procedures such as the gastric sleeve or the gastric bypass.

This 2025 guide compares 7 major KiwiSaver providers based on:

• Medical withdrawal flexibility

• Hardship approval difficulty

• Documentation requirements

• Processing speed

• Bariatric surgery–specific outcomes (based on real patient feedback)

• Overall ease of working with them

If you haven’t read the full overview yet, see the main guide:

👉 KiwiSaver for Weight Loss Surgery (2025 Guide)

🟦 SUMMARY TABLE — QUICK COMPARISON (2025)

Most bariatric-friendly providers (based on real patient outcomes):
👉 Booster, Fisher Funds, and Aurora

🟧 1. Booster KiwiSaver

⭐ Best overall provider for bariatric surgery applicants (2023–2025 feedback)

Booster stands out for its balance of:

• Reasonable documentation requirements

• Willingness to accept strong GP medical letters

• Predictable review process

• Faster-than-average turnaround times

Medical Withdrawal

Booster accepts medical withdrawal applications where:

• Surgery is clinically recommended

• Non-surgical interventions have failed

• Health is at risk if surgery is delayed

They often request:

• GP letter

• Specialist notes (if available)

• BMI + comorbidities

• Treatment history

Hardship Withdrawal

Medium difficulty — they want:

• 3 months of bank statements

• Income & expense summary

• Reasonable proof of inability to pay upfront

Processing Time

7–12 business days.

Bariatric Surgery Suitability

⭐ One of the highest approval rates based on patient feedback.

🟩 2. Fisher Funds KiwiSaver

⭐ Very clear, structured, and easy-to-follow process

Patients report Fisher Funds as:

• Communicative

• Predictable

• Transparent about what they need

Medical Withdrawal

They accept GP-led medical cases if the documentation is complete.

Required:

• GP letter

• Any specialist notes

• Clear diagnosis + BMI

• Treatment history

• Cost estimate

Hardship Withdrawal

Medium difficulty — they expect strong financial evidence but do not overcomplicate the process.

Processing Time

7–14 business days.

Bariatric Surgery Suitability

⭐ Strong choice — good balance of formality + fairness.

🟦 3. Aurora KiwiSaver

⭐ Fastest hardship decisions (based on patient experience)

Aurora is less widely known but surprisingly efficient for hardship cases.

Medical Withdrawal

Moderate acceptance — relies heavily on GP letter quality.

Hardship Withdrawal

Known for:

• fast processing

• simple requirements

• easy communication

They typically request:

• Bank statements

• Income details

• GP letter (if related to medical hardship)

Processing Time

5–10 business days → one of the fastest.

Bariatric Surgery Suitability

⭐ Excellent for hardship-focused applicants.

🟫 4. Milford KiwiSaver

⭐ Strong on medical, strict on hardship

Milford generally takes a fair but high-standard approach.

Medical Withdrawal

Very reasonable as long as:

• GP letter is detailed

• Comorbidities are outlined

• Necessity is clear

Hardship Withdrawal

Strict. They:

• examine spending

• question discretionary expenses

• request full documentation

• may require a statutory declaration

Processing Time

5–10 business days.

Bariatric Surgery Suitability

✔ Good — as long as documentation is strong.

🟧 5. Simplicity KiwiSaver

⚠️ The strictest provider for hardship applications

Simplicity is known for:

• deep financial scrutiny

• requesting additional documents

• longer review times

Medical Withdrawal

Possible, but they want:

• detailed GP statement

• strong justification

• treatment history summary

Hardship Withdrawal

Very strict — they may request:

• 3–6 months bank statements

• detailed budgets

• proof of loan declines

• statutory declaration

• proof that no other funding source exists

Processing Time

10–20 business days.

Bariatric Surgery Suitability

🔸 Challenging.

Not recommended unless the case is extremely strong

🟩 6. ANZ KiwiSaver

✔ Balanced, fair, predictable

ANZ requires:

• Complete medical documentation

• Detailed GP letter

• Transparent financial summaries

Medical Withdrawal

They want clear risk statements:

• “Delaying surgery will worsen X”

• “Non-surgical attempts failed”

• BMI + comorbidities

Hardship Withdrawal

Medium difficulty — not overly strict, but thorough.

Processing Time

8–15 business days.

Bariatric Surgery Suitability

✔ Good — especially for medical-focused applications.

🟨 7. AMP KiwiSaver

✔ Accepting but often asks for extra documentation

AMP generally interprets the rules conservatively but fairly.

Medical Withdrawal

They often ask for:

• GP letter

• Treatment history

• Proof of why surgery is medically necessary

Hardship Withdrawal

Medium difficulty — expect:

• Expense breakdown

• Income verification

• Bank transactions

• Possibly a budget worksheet

Processing Time

10–15 business days.

Bariatric Surgery Suitability

✔ Acceptable — but may require follow-ups.

🟪 Which Provider Is Best for Weight Loss Surgery?

Based on patient feedback, approval consistency, communication, and processing speed, the top 3 are:

🥇 1. Booster

Most balanced, highest approval confidence.

🥈 2. Fisher Funds

Clear, structured, reliable.

🥉 3. Aurora

Fast hardship approvals, simple process.

If you haven’t chosen a provider yet, or you’re thinking of switching in the future, these three are the most bariatric-friendly options.

📝 Additional Tips When Applying

Regardless of provider:

✔ Submit a very detailed GP letter

→ Use our template:
KiwiSaver GP Letter Template

✔ Include all documents in one email/PDF

Reduces delays.

✔ Be honest and transparent

Providers cross-check income & expenses.

✔ Do not ask to withdraw your full balance

Only request the surgery amount.

✔ Follow up after 5–7 business days

Many providers speed up when politely reminded.

🔗 Want to understand the full process?

See the main guide:
👉 KiwiSaver for Weight Loss Surgery (2025 Guide)