Duet
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How Duet works

One platform. Two prices.
The customer chooses.

Walk the full customer journey, run the worked $100 math, see what the platform does, and get straight answers on the questions merchants ask.

The customer journey

Both prices, every step of the way.

This continuity is what makes Duet compliant. There is no surcharge added at checkout — the two prices have been there all along.

01
Estimate sent

You build an estimate the way you always have — line items, optional sign-to-accept. The recipient sees the ACH / Cash price and the Card price side by side, line by line. Signed estimates carry both prices on the PDF audit certificate.

Estimate · EST-0084
SIGN TO ACCEPT
Item
Qty
ACH / CASH
CARD
Labor
10
$250.00
$260.00
Product 1
1
$250.00
$260.00
Silver service
1
$250.00
$260.00
Subtotal
$1,000.00
$1,040.00
Sales tax
$50.00
$52.00
Total
$1,050.00
$1,092.00
ACH / CASH
$1,050.00
CARD
$1,092.00
Choose ACH / Cash and save $42.00.
Estimate expires June 25, 2026 · A signature is required to accept.
02
Invoice email

The invoice email itself shows both prices — not just the link. Subject, body, and the inline summary all carry the dual-price disclosure, so the customer can decide before they even click through.

From: AutomateWithUs <billing@automatewith.us>
Subject: Invoice 2026-000050 — amount due
Hi Drew,
Your invoice is ready. Pay by bank or card — both prices below.
Invoice 2026-000050
Due May 30
ACH / CASH$817.50
CARD$850.20
Questions? Reply to this email — we read every one.
03
Hosted invoice page

A clean, mobile-friendly invoice doc — bill-to and from blocks, line items in ACH / Cash and Card columns, subtotal, sales tax, amount due. The savings line spells out exactly how much the customer keeps by paying ACH.

Invoice
2026-000050
D
AutomateWithUs
Bill to
Drew Jacobs
Sherman, IL 62684
From
AutomateWithUs
Springfield, IL 62703
Description
ACH / CASH
CARD
Labor
$250.00
$260.00
Gold service
$100.00
$104.00
Product 1
$250.00
$260.00
Product 2
$150.00
$156.00
Amount due
$817.50
$850.20
Save $32.70 when you pay by bank instead of card.
04
Customer checkout

The payment moment. One-click pay with a stored bank or card if the customer has used you before, plus the two big payment-method buttons — ACH on top, card below — each showing its price with the savings note inline on ACH.

Pay in 1-click
VISA ·1111
exp 11/29 · Pay $212.56
Bank ·019
checking · Pay $204.38
Or pay with a new method below.
05
Refunds & audit

Every event is timestamped: estimate sent, accepted, invoice sent, payment, refund. Refunds go back in the path the customer paid. Both prices remain on the audit trail forever.

Audit trail
Invoice 2026-000050
REFUNDED
Event
ACH / CASH
CARD
Estimate sent
May 22 · 09:14
—
—
Estimate accepted
May 22 · 09:31
—
—
Invoice 2026-000050 sent
May 26 · 10:02
$817.50
$850.20
Customer paid · ACH
May 26 · 10:15
$817.50
—
Refund issued · ACH
May 26 · 14:48
−$817.50
—
Refund issued in the path the customer paid. Both prices remain on the record.
The worked example

On a $100 invoice,
at 5.0% Dual Price.

Drag the slider to see how the numbers move. Default is 5% — comfortable margin on card. Slide down toward 3% to “split the freight” with the customer. Slide up for margin on card.

Dual Price %
5.0%
Split the freight · 2%Default · 5%Margin on card · 10%
Customer pays by card$105.00
Square processing · 2.9% + $0.30−$3.35
Duet platform fee · 1%−$1.05
Deposited to your bank$100.61
Today, absorbing fees$96.80
You gain+$3.81
The ACH promise

Duet never charges a fee on bank payments.

Not a cut, not a fee — nothing. ACH is the cheaper-for-everyone path. Square’s own standard ACH rate still applies (1%, capped at $10), but you’ll never read a Duet fine-print line on a bank transaction.

On a $100 ACH payment
Customer pays$100.00
Duet fee$0.00
Square's ACH (1%, capped $10)−$1.00
Deposited to your bank$99.00
What’s in the platform

Everything you’d expect from an invoicing tool. Plus the dual-pricing engine.

Invoicing
Send dual-priced invoices by email or text. Customer pays on a hosted page on duetpay.io that you can brand.
Estimates
Send dual-priced estimates with optional sign-to-accept. Estimates convert to invoices in one click. Signed estimates carry a PDF audit certificate with timestamp + IP.
Reusable packages
Build a package template once (e.g. 'small print job'), send variations to many customers.
Public payment pages
Donation pages (one-time or recurring), invoice lookup, registration / signup, auction pay. Customers can pay without an invoice being created first.
Embeddable widgets
Drop a 3-line script into your existing site. Works cross-origin and looks like part of your own brand.
QR code generator
Branded QRs that point at any Duet page or external URL. Useful for in-person collection, event signage, mailers.
Customer & catalog
Saved customers, contact info, payment history. Reusable line items with bank + card pricing pre-built.
Recurring & reminders
Recurring giving and invoicing with stored bank- or card-on-file. Automated overdue and upcoming-due reminders, configurable per merchant.
Refunds & audit
Full refund support in both payment paths, with reconciliation back to Square. Every action timestamped and visible.
Is this legal?

Short answer: yes — in all 50 states.

State-by-state rules around how merchants can pass card processing costs to customers are complex and changing. There are two main models — and Duet is built around the one that’s universally allowed.

Surcharge
Adds a fee on top of the listed price at checkout. Heavily regulated. Banned or restricted in several states. Requires registration with card networks. Carries disclosure rules small merchants frequently miss.
Dual pricing — what Duet does
Two real prices, disclosed upfront throughout the customer experience. Legal in all 50 states when both prices are visible at every step. Duet builds those disclosures into every email, payment page, and receipt.

You don’t need to think about compliance — the disclosures live in the platform. You just send invoices.

FAQ

The questions merchants actually ask.

Ask us something else →
Is this a surcharge program?
No. A surcharge is a fee added on top of the listed price at checkout — heavily regulated and restricted in several states. Duet shows two real prices from the start, throughout the entire customer experience (estimate, invoice, email, payment page, receipt). That's dual pricing, and it's legal in all 50 states.
Is this legal in my state?
Yes — dual pricing, done the way Duet does it (both prices disclosed at every customer touch point), is legal in all 50 states. We build the required disclosures into the platform so you don't have to manage them yourself.
What does my customer actually see at checkout?
Two large payment-method buttons. Bank on top, card below — each showing its price. The bank button is highlighted with a 'best price — save $X' note inline. Both prices have already been visible to them at every prior step, so there are no surprises.
Do I need a new payment processor?
No. Duet is built on top of your existing Square account. Square is the merchant of record, processes the card, and deposits the money. We never touch card numbers and we never sit in front of your deposits.
Does the money still land in my Square account?
Yes — every payment lands in your Square account, on the same schedule as your other Square deposits. Duet's small per-transaction take is collected through Square's app-partner mechanism.
What happens if a customer disputes a charge?
Disputes flow through Square the way they always have. Duet's audit trail — both prices visible at every step, plus signed-estimate certificates where applicable — gives you strong documentation to respond with.
Can I send recurring invoices?
Yes. Customers and donors can opt into recurring giving or recurring invoicing with bank-on-file or card-on-file. The dual-price disclosure applies to recurring runs just like one-off invoices.
Can I embed this on my own website?
Yes. Every public payment page (donations, invoice lookup, signup, auction) can be embedded into your existing site with a three-line script snippet. It works cross-origin and inherits your site's look.
What does it cost me?
Duet charges a flat 1% platform fee on card transactions and zero on bank transactions. There's no monthly subscription, no setup fee, no contract. Square's own processing rates apply on top, as they always have. Full breakdown on the pricing page.
How long does setup take?
About five minutes — connect Square via OAuth, set your Dual Price % (default 5%), send your first dual-priced invoice.

Ready to keep what you earn?

Connect Square, set your Dual Price %, send your first dual-priced invoice — about five minutes, no contract.

Get started See pricing