What is ACH transfer?

A United States bank transfer network that exchanges use for free or low-cost dollar deposits, usually clearing in one to three business days.

Because ACH payments can be reversed by the sender's bank, most exchanges hold the crypto you buy with them for several days before allowing a withdrawal. Compare wire transfer, which is faster and final.

ACH is the default funding rail for United States buyers because it is usually free at the exchange and cheap for the bank. The thing people get wrong is treating the trade as settled the moment it fills. Your order executes immediately, but the dollars behind it have not finished moving, and the exchange manages that gap by locking the coins.

How it works

ACH is a batch network, not a real-time one. Your instruction is queued, sent to an operator, and settled between banks on a later processing window. The rules are set by Nacha and the network is operated by the Federal Reserve's FedACH service and The Clearing House's Electronic Payments Network.

A crypto exchange funding a purchase this way normally initiates a debit against your bank account. It credits your dollar balance right away on the assumption the debit will clear, then waits before letting anything leave the platform.

The waiting exists because ACH debits can be returned. Nacha's operating rules give a receiving bank a defined window to return an entry, and an unauthorized consumer debit carries a longer window than an ordinary administrative return. The exact windows vary by return reason, so exchanges publish their own hold periods rather than quoting the rules.

Same Day ACH exists and some institutions use it, but crypto exchanges rarely pass the speed through, because their exposure comes from the return window rather than from settlement timing.

Example

Illustrative: you deposit $1,000 by ACH on a Monday and buy immediately. The dollars appear in your account within minutes and the order fills at the market price. The exchange applies a hold, so the coins cannot be withdrawn until the following week. If the price doubles on Tuesday, you own the gain but cannot move the asset off the platform. If you had used a wire, the same $1,000 would typically cost a wire fee of tens of dollars and carry no hold. Numbers are illustrative; fees and hold lengths vary by exchange.

Why it matters when you buy

The choice between ACH and a wire is a trade between cost and control. ACH is usually free and slow to release; a wire usually costs money and releases immediately. If you intend to move coins to self custody straight after buying, the hold is the deciding factor rather than the fee. Check what each venue charges for each funding method at the fee comparison, and check the venues available to you at the exchange directory.

Related terms

• wire transfer — faster and final, but usually paid for
• sepa — the euro-area equivalent rail
• chargeback — the card-network version of a reversal
• withdrawal limit — what the platform lets you move and when
• minimum deposit — the floor on a funding transfer
• fiat gateway — the plumbing that turns dollars into a balance

Questions

Why can I trade instantly but not withdraw?

The exchange credits you before the money has finished clearing, then holds the asset until the return window on your deposit has passed. The trade is real; the settlement behind it is not finished.

Is ACH cheaper than a card?

Almost always. Card purchases carry a processing charge that is commonly a few percent, while ACH deposits at major United States exchanges are often free. Check the venue's own fee page, because this varies.

Can I use ACH from outside the United States?

No. ACH is a domestic United States network. Buyers elsewhere use their own local rails, such as SEPA in the euro area or Faster Payments in the United Kingdom.