What is an ACH Automated Clearing House?

ACH (Automated Clearing House) is a US bank-to-bank payment network that moves money directly between bank accounts without credit cards, wires, or paper checks. The network is operated by Nacha and processes more than 30 billion transactions per year, covering payroll, direct deposit, recurring bill payments, tax refunds, and most US B2B invoice settlement.

Why does ACH exist?

Before ACH, US bank-to-bank payments meant paper checks, wires, or cash. Checks were slow and lossy. Wires were expensive (often $25-$50 per send) and hard to automate. In 1974, Nacha was set up as a nonprofit consortium of banks, credit unions, and clearing houses to run a shared electronic network for low-cost, batched, account-to-account payments.

The network now settles trillions of dollars a year. Payroll runs on ACH. Most utility bills, mortgage payments, insurance premiums, and B2B invoices in the US run on ACH. Tax refunds run on ACH. If you receive direct deposit, you receive ACH.

How does an ACH payment actually work?

Every ACH payment involves five parties:

1. The originator. The business or person initiating the payment. For a SaaS company billing a customer, this is the SaaS company.

2. The Originating Depository Financial Institution (ODFI). The originator's bank, which submits the request to the ACH network.

3. The ACH operator. Either the Federal Reserve (FedACH) or The Clearing House. The operator batches transactions and routes them between banks.

4. The Receiving Depository Financial Institution (RDFI). The customer's bank, which debits or credits the customer's account.

5. The receiver. The customer or counterparty whose account is being moved.

ACH is batched, not real-time. The ODFI collects transactions during the day, packages them into NACHA-format files, and submits them at fixed windows. The ACH operator processes those windows and forwards files to the RDFI. The RDFI posts the credit or debit to the receiver's account on the settlement date.

Settlement windows currently land at 1:00 p.m., 5:00 p.m., and 6:00 p.m. ET for same-day ACH, with next-day and two-day windows available for lower fees.

ACH credit vs ACH debit: what's the difference?

The two ACH transaction types describe which side initiates the money movement.

ACH credit (push). The originator pushes money out of their account into someone else's. Payroll is the canonical example: the employer pushes payment to the employee's bank account. ACH credit needs no authorization from the recipient.

ACH debit (pull). The originator pulls money out of a customer's account, with prior authorization. Recurring SaaS billing, utility autopay, and subscription charges run on ACH debit. The originator must hold a signed or electronic mandate from the customer authorizing the debit, and Nacha rules govern how long that authorization is valid.

Most B2B and subscription billing in the US runs on ACH debit. That's the side of the network billing platforms spend most of their time on.

How long does ACH take to settle?

Standard ACH settles in 1-3 business days. Same-day ACH was introduced in 2016 and expanded in 2021. It now covers transactions up to $1 million per transfer.

The hidden tail: ACH returns can come back up to 60 days after the original transaction for unauthorized debit disputes, and 2 business days for non-sufficient funds (NSF). A return is what happens when an ACH debit fails after settlement, typically because the account was closed, the funds weren't there, or the customer disputed the authorization. Returns arrive as R-codes (R01 through R85), and any billing system that runs ACH needs to handle them.

What does ACH cost?

ACH is the cheapest mainstream US payment rail. Cost varies by provider:

• Direct bank ACH origination. Pennies per transaction at the bank level. Most large enterprises run direct.

• Stripe ACH Direct Debit. 0.80%, capped at $5. A $625 invoice costs $5 in fees.

• Adyen ACH. Per-transaction pricing, typically sub-$1 for B2B volumes.

• Modern Treasury, GoCardless, similar API banks. Flat per-transaction or volume tiers, usually under $1 for high-volume merchants.

Compare that to cards. A $10,000 B2B invoice on a credit card costs $250-$300 in interchange and processing. The same invoice on ACH costs under $5. For any business with average ticket above $200, ACH is the cost-rational rail.

How does ACH compare to wires, cards, and RTP?

ACH and SEPA Direct Debit are functionally the closest pair. If you're scaling a US billing operation into Europe, SEPA is the rail that fills the same job.

What can go wrong with ACH?

ACH has a different fraud and failure profile than cards. The most common failure modes:

• NSF (R01). The customer's account didn't have the funds. Typical retry behavior: wait 2-3 days, retry once or twice, then escalate to dunning.

• Account closed (R02). Customer changed banks. Needs a new mandate.

• No authorization on file (R07, R10, R11). The customer disputed the debit. Nacha rules give consumers 60 days to dispute unauthorized debits, which means returns can show up well after the invoice was marked paid.

• Invalid account / routing (R03, R04). Caught by upfront bank verification (Plaid, Stripe Financial Connections, or micro-deposits).

• Failed micro-deposit verification. Customer didn't confirm the test amounts. The mandate is never created.

A billing system that supports ACH needs to handle all of this. Failed debits need automatic retries with backoff. Returns need to reverse the invoice status and re-open the receivable. Disputes need to be escalated to collections. None of this happens with card payments because cards either authorize or decline at the point of sale.

How ACH fits into a billing platform

Most billing platforms list ACH as a supported payment method. Implementation quality varies. The things that separate a real ACH implementation from a brochure entry:

• Bank account verification. Plaid-style instant verification beats micro-deposits on conversion. Both should be available.

• Authorization capture. The system records the mandate (signed PDF, electronic acceptance, voice authorization) and keeps it auditable.

• Returns handling. The system listens for R-codes from the processor, updates invoice status, and triggers downstream workflows (retry, dunning, manual review).

• Multi-rail orchestration. Customers don't all pay the same way. A real implementation lets a customer pay invoice 1 via ACH, invoice 2 via wire, and invoice 3 via card without manual reconciliation.

• Same-day vs next-day routing. For cash flow optimization, the system should route urgent debits to same-day windows and routine debits to next-day for lower fees.

A billing platform that supports ACH alongside cards, wires, and SEPA, and reconciles all of them back to the same invoice ledger, is doing meaningfully more work than a payment gateway that just accepts ACH at checkout.

Where Solvimon fits

Solvimon supports ACH natively through our Adyen for Platforms integration, and through Stripe or Checkout.com when customers bring their own processor. ACH debits, returns, and same-day routing live in the same Invoicing and Payment Methods primitives as card payments, so reconciliation runs through a single ledger rather than across multiple systems.

Related terms

• SEPA Direct Debit

• Dunning

Frequently asked questions

What does ACH stand for?

ACH stands for Automated Clearing House. It's the US bank-to-bank electronic payment network operated by Nacha.

Is ACH the same as direct deposit?

Direct deposit is one use of ACH. When your employer pays you via direct deposit, that's an ACH credit transaction. ACH covers many other types of payments beyond payroll.

Is ACH the same as a wire transfer?

No. ACH uses the Nacha network and settles in batches over 1-3 business days. Wire transfers use Fedwire or SWIFT and settle within hours, but cost $15-$50 per transaction and aren't reversible.

Can ACH be used internationally?

No. ACH is US-only (plus Puerto Rico). For cross-border payments, businesses use wires, SEPA Direct Debit in the eurozone, or local rails in other regions. Some processors will let you fund an international payout from a US ACH source, but the actual cross-border leg uses a different network.

How long does ACH take?

Standard ACH settles in 1-3 business days. Same-day ACH is available for an additional fee and clears within the same business day in most cases.

What's the difference between ACH credit and ACH debit?

ACH credit means the originator pushes money out of their account (e.g., payroll). ACH debit means the originator pulls money from a customer's account, with prior authorization (e.g., subscription billing).

How much does ACH cost a business?

At the bank level, ACH costs pennies per transaction. Through processors like Stripe, ACH costs 0.80% capped at $5. Through Adyen or direct ACH origination, costs are typically sub-$1 per transaction for high-volume merchants.

Why do ACH payments get returned?

ACH returns happen for several reasons: non-sufficient funds (R01), closed accounts (R02), disputed authorization (R07, R10, R11), or invalid account details (R03, R04). Returns can arrive up to 60 days after the original transaction for unauthorized debit disputes.

Is PayPal an ACH payment?

PayPal isn't an ACH network by itself. PayPal uses ACH to move money in and out of bank accounts when you link a US bank account to your PayPal balance. The PayPal balance itself is a separate ledger.

What should I look for in a billing platform that supports ACH?

Bank account verification (Plaid plus micro-deposit fallback), automatic returns handling (R-code reconciliation), multi-rail orchestration (so the same customer can pay via ACH or card without manual work), same-day routing for cash flow, and a unified ledger that reconciles all payment methods to the same invoice.

Solvimon supports ACH for US customers as one payment method among many. For implementation details, see our payment methods overview.