Stax Review 2026: Pricing, Fees & Is It Worth It?

Stax (formerly Fattmerchant) takes a completely different approach to payment processing than Square, Stripe, or PayPal. Instead of charging a percentage markup on every transaction, Stax charges a flat monthly subscription fee and passes interchange directly to you at cost — with only a few cents per transaction added on top.

For the right business, this model can save thousands of dollars per year. For the wrong business, it’s an expensive mistake. This review breaks down exactly who benefits from Stax and who doesn’t.

Want to see how Stax compares to other processors for your volume? Use our free fee calculator or compare all processors side by side.

Stax Review 2026: Quick Summary

What is Stax?

Stax is a Florida-based payment processor founded in 2014 (originally as Fattmerchant, rebranded to Stax in 2021). It processes over $30 billion in payments annually for more than 30,000 businesses.

Stax’s core differentiator is its subscription pricing model — you pay a fixed monthly fee based on your annual processing volume, and in return you get interchange at wholesale cost with zero percentage markup. You only pay a few cents per transaction on top of the actual interchange fee.

This is fundamentally different from flat-rate processors (Square, Stripe, PayPal) and even traditional interchange-plus processors like Helcim. The model works best for businesses with consistent, high volume — and poorly for businesses with unpredictable or low volume.

Stax Pricing 2026

Stax uses three subscription tiers based on annual processing volume:

Key point: The per-transaction fees are the same across all plans — the monthly fee is what changes. The average interchange rate is approximately 1.81% for in-person and 2.20% for online transactions, meaning your effective rate is typically around 1.89% + $0.08 in-person and 2.35% + $0.15 online — competitive but not automatically cheaper than alternatives without doing the math for your specific volume.

What’s Included in All Plans

• Stax Pay — in-person, mobile, and online payment acceptance
• Stax Bill — invoicing and recurring billing
• Real-time reporting and analytics dashboard
• Digital invoicing and payment links
• Mobile app for payment management
• API access for custom integrations
• ACH and bank transfer processing
• CardX surcharging (available as add-on)

Is Stax Actually Cheaper?

Stax is cheaper than flat-rate processors — but only above a certain monthly volume. The monthly subscription fee is the critical variable. Here’s the math:

$10,000/Month In-Person Volume

At $10,000/month, Stax is actually more expensive than Helcim and only slightly cheaper than Square — the $99 monthly fee offsets the transaction fee savings.

$20,000/Month In-Person Volume

At $20,000/month, Stax beats Square and Stripe but is still more expensive than Helcim due to the monthly fee. Helcim uses interchange-plus pricing with no monthly fee — making it cheaper at most volume levels.

When Does Stax Win on Price?

Stax becomes cost-competitive primarily when you’re on the Pro or Ultimate plan ($139-$199/month) and processing $150,000+/year — at that volume, the subscription model delivers real savings over flat-rate processors. Against Helcim, the math is tighter because Helcim has no monthly fee.

Stax Features

Stax Pay — In-Person and Mobile Payments

Stax is hardware-agnostic — it works with most third-party POS systems including Clover, Dejavoo terminals, and others. This is a genuine advantage if you already have hardware you like. Stax also offers a mobile app and Bluetooth card reader for mobile payments.

Stax Bill — Invoicing and Recurring Billing

Stax Bill covers invoicing, recurring billing, and subscription management. For B2B businesses or service companies that invoice clients regularly, this is a strong feature set comparable to what Helcim offers for free.

Stax Connect — Embedded Payments for SaaS

Stax Connect allows software companies and ISVs to embed payment processing directly into their platforms. This is Stax’s enterprise offering and most differentiated product — not relevant for most small businesses.

CardX Surcharging

Stax offers compliant credit card surcharging via CardX integration starting at $99/month as an add-on. If you want to pass processing fees to customers, this is a built-in compliance solution.

Stax Pros

• ✅ 0% percentage markup — you pay only interchange + cents per transaction
• ✅ Hardware-agnostic — works with most third-party POS systems
• ✅ Month-to-month contracts — cancel anytime with no penalty
• ✅ All features included — invoicing, recurring billing, reporting all in one
• ✅ Good for high-volume B2B — subscription model rewards consistent, predictable volume
• ✅ Transparent pricing model — no percentage markups hidden in your rate

Stax Cons

• ❌ Monthly fee is expensive for low volume — $99/month makes it uncompetitive below $8,000-$10,000/month
• ❌ Still more expensive than Helcim — Helcim has no monthly fee with comparable interchange-plus rates
• ❌ Chargeback fees not disclosed publicly — you have to request this in your merchant agreement
• ❌ No proprietary hardware — you buy from third parties, no ecosystem like Square or Clover
• ❌ Customer service complaints — reviews mention slow response times and billing disputes
• ❌ Next-day funding not guaranteed — competitors offer this for free; Stax may charge extra
• ❌ Onboarding issues reported — some users experienced setup problems during processor switching

Stax vs Competitors

Who Should Use Stax?

Stax makes the most sense for:

• Businesses processing $150,000+/year ($12,500+/month) with consistent volume
• B2B service businesses with regular invoicing needs
• Businesses already owning POS hardware they want to keep
• SaaS companies needing embedded payment processing via Stax Connect
• Businesses wanting a 0% markup model and don’t mind the monthly fee

Stax is not a good fit for:

• Businesses processing under $10,000/month — the monthly fee kills the savings
• Restaurants — no table management, KDS, or restaurant-specific POS features
• Seasonal businesses — you pay the monthly fee even in slow months
• Businesses wanting the absolute lowest fees — Helcim’s no-monthly-fee interchange-plus model typically wins

Stax vs Helcim: Which Is Cheaper?

This is the most important comparison for businesses considering Stax. Both use interchange at cost — but Helcim charges a small percentage markup (0.40%) while Stax charges a flat monthly fee instead.

The break-even point where Stax becomes cheaper than Helcim on the Growth plan ($99/month) is approximately $24,750/month in in-person volume. Below that, Helcim wins on total cost. Above that, Stax edges ahead — but the gap is small.

For most small businesses, Helcim is the simpler and cheaper choice because there’s no monthly fee risk.

Real User Reviews

Based on verified reviews from G2, Capterra, and other platforms:

• Pricing model: Widely praised for transparency — users appreciate seeing the actual interchange cost
• Savings: High-volume users report meaningful savings; some report actual savings were lower than initially promised
• Customer service: Mixed — some users report excellent support, others describe slow response times and difficulty resolving billing disputes
• Onboarding: Several reviews mention issues during processor switching, including setup errors that caused delayed payments
• Interface: Consistently rated as easy to use and well-designed

Our Verdict: Is Stax Worth It?

Stax is a legitimate, well-designed processor with a genuinely transparent pricing model. For businesses processing $150,000+/year with consistent monthly volume, the subscription model can deliver real savings over flat-rate processors like Square and Stripe.

However, for most small businesses, Helcim is a better choice — it uses the same interchange-at-cost model but charges no monthly fee and no percentage markup above $50,000/month. The math usually favors Helcim unless you’re processing very high volumes.

If you’re specifically attracted to the subscription model and process $12,500+/month consistently, Stax is worth evaluating. Just request a full fee disclosure before signing — chargeback fees and other costs aren’t publicly listed.

Our rating: 4.1/5 — good for high-volume businesses, but not the best fit for most small businesses.

Use our free fee calculator to compare Stax against Helcim, Square, and Stripe at your exact monthly volume, or see all processors side by side.

Frequently Asked Questions: Stax Review