What is a memo in crypto? The second address some coins need, and the one time you leave it empty.

01A memo is a second address

An address gets coins to a wallet. A memo gets them to the right person behind that wallet.

xrpl.org explains it in two lines. Destination tags "indicate the beneficiary or destination for a payment", such as which customer to credit. And they "do not have direct on-ledger functionality".

So the chain delivers to the address, and that's all it does. The exchange's own database reads the tag. Get the address right and the tag wrong, and your coins arrive somewhere nobody is looking. The main guide on how to swap crypto puts this in the full picture.

02Why exchanges share one address

Bitcoin-style coins give every customer a fresh address, so they never needed memos. Other chains make that expensive.

• XRP Ledger: an address must be a funded account, and the reserve "must be set aside indefinitely for each address". One address with tags avoids paying that per customer.
• Stellar: pooled accounts mean "no base reserves are needed for each account".
• TON: services use "one wallet address to receive payments from all users", with lower costs as the reason.

Bottom line: the memo is the price of a cheaper deposit system, and the sender carries the risk.

03Which coins use one, and what each must look like

Here's the table nobody else publishes: each chain's word, and its rule, from its own docs.

USDT on TON carries its comment with the token transfer, so it follows TON's rule.

04Memo, tag, comment, note: one idea, five names

"Memo vs tag" is a naming question, not a technical one. Each chain uses its own word, and exchanges relabel them freely.

• Tag on XRP, because it's always a number. Paste text into an XRP tag field and it fails.
• Memo on Stellar, Cosmos and Hedera: text, or on Stellar a number too.
• Comment on TON, which is literally a wallet text message.
• Note on Algorand: free data attached to the payment.

05Will the chain stop you? XRP can, Stellar asks, the rest don't

This is the section every other guide skips, and it decides whether a mistake costs you anything.

XRP Ledger. A receiver can switch on a flag so that "the XRP Ledger rejects any payment to your address if it does not specify a destination tag". Then: "The user can then send the payment again, using the tag as they should have."

Stellar. An account can publish that it needs a memo, and the sender's wallet is asked to stop you. It's a wallet convention, not a ledger rule, so an older wallet can still send.

TON and Cosmos. Nothing on the chain checks. TON's own docs warn that deposits "without the correct invoice identifier may be lost".

Our readingHow many receivers switch the safety net on?

We read 100 consecutive XRP Ledger ledgers on 3 November 2026, about seven minutes of traffic, from a public server:

So the safety net exists, but most receivers haven't switched it on. The check is yours.

06Forgot the memo? What happens and what to do

First, what happens. It depends entirely on the receiver:

If the payment landed, the coins sit on the shared address and, as xrpl.org puts it, "it is not immediately obvious which customer to credit". Nothing on the chain can reverse it. Then, in order:

1. Don't send again. A second payment without the memo just doubles the problem.
2. Find the transaction ID in your wallet's history.
3. Write to the receiver's support with the transaction ID, the amount, the time and your deposit memo. Each service sets its own process.

you send 50 XRP to an exchange and leave the tag empty. If the exchange set the flag, the payment fails and the 50 XRP are still yours, minus the network fee, which a failed payment still burns. If not, the 50 XRP wait under no name until support matches your transaction ID.

Monero's own history proves this is a support job. It removed long payment IDs because users who forgot them "have to go through support to 'recover' their funds".

07Sending to your own wallet: leave it empty

A memo only matters when one address has many owners. Your own wallet has one.

• Leave it empty when your wallet's receive screen shows only an address.
• Use the memo when the receive screen shows one. That means the "wallet" is really an account at a service, sharing an address.
• Never invent a memo for a receiver that gave you one. A made-up number can land on someone else's account.

08The fixes that remove the memo

A memo is a workaround, and the chains are retiring it by folding it into the address.

• Stellar: muxed M addresses carry the ID inside, though Stellar notes they "aren't yet supported by all wallets, exchanges, and anchors".
• XRP Ledger: an X-address combines the classic address and the tag in one string.
• Monero: wallets use subaddresses by default, and businesses can use integrated addresses.

When a service offers one address with the memo built in, prefer it. One thing to copy is one thing to get right. Our desk takes both: paste an X-address or an M address and it splits it into the address and the tag for you.

09Does this send need a memo?

Pick the coin and where it's going. If you were given a memo, paste it to check its format against the chain's rule.

10What our desk does

Swapping XRP for privacy? Start with XRP to Monero, where the coin you receive needs no memo at all, on our swap with no ID.