Why do some cross-chain swaps ask for a memo or destination tag and what happens if you leave it blank

05 September 2026

Some cross-chain swaps ask for a memo or destination tag because the receiving blockchain uses a single deposit address for multiple users, and the tag tells the exchanger whose funds have arrived. If you leave it blank, the exchanger cannot identify your transaction. Your funds will likely be lost or frozen until you contact support, and recovery may take days or never happen.

The memo or destination tag is not a random extra step. It exists because certain blockchains - most notably XRP Ledger, Stellar, and some exchanges that use integrated wallets - assign one deposit address to many customers. When you send tokens to that address, the blockchain sees only the address. The tag is an extra piece of data carried alongside the transaction. It functions like a room number in a hotel: the building address gets you to the front desk, but without the room number, the staff does not know where to deliver your luggage.

Here is what actually happens inside a cross-chain swap without a bridge. You give the exchanger your destination address on the target chain. The exchanger generates a deposit address on the source chain - often their own pooled wallet. You send your coins there. The exchanger watches that address, sees the incoming transaction, and reads any attached memo or tag. If the tag matches a record in their database, they credit your swap and release the other asset on the target chain. If there is no tag, they see an incoming transaction with no identifying information. They have no way to link it to your swap order.

The consequence of leaving the tag blank is not a technical error - it is an operational dead end. Your coins arrive safely at the exchanger’s address. They are not lost to the void. But the exchanger has many incoming transactions to that address every day, each belonging to a different user. Without the tag, they cannot tell yours apart from anyone else’s. Customer support can sometimes recover the funds by cross-referencing timestamps, amounts, and source addresses, but this is a manual process. The exchanger will likely charge a recovery fee, and the timeframe can range from hours to weeks. Some smaller or automated exchangers simply ignore untagged deposits entirely.

Common chains that require a tag include: - XRP (Ripple) - destination tag required - Stellar (XLM) - memo ID required - Binance Smart Chain (BSC) - sometimes a memo from exchange-to-exchange transfers - EOS - memo required - Cosmos (ATOM) - memo used for exchange deposits - Some ERC-20 tokens when sent to exchange-managed wallets that pool addresses

Not all swap services treat the tag the same way. A reputable exchanger will display a clear warning before you confirm the transaction if the tag field is empty. Others will reject the order at the deposit stage. A few will accept the swap without a tag and then freeze the deposit until you contact them. The safest approach is to treat the memo or destination tag as mandatory whenever the field appears. Copy it exactly, including case and leading zeros. Some tag formats include letters; all of them matter.

If you are using a cross-chain swap that routes through an automated exchanger, the tag is typically generated for that single order and expires once used. Reusing an old tag from a previous swap will cause the exchanger to credit the wrong order - or fail to credit anything.

For a full explanation of what actually moves between blockchains when you use this kind of swap - and to see why your tokens are never truly “sent” across chains - read the sibling page titled What actually moves between blockchains when you do a cross-chain swap without a bridge.

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