Transactions, UTXOs & fees

Dogecoin has no account balances. That sentence surprises everyone the first time. What the chain actually stores is a pile of spendable coins – UTXOs – and a "balance" is just the sum of the ones your keys can unlock. Get this model into your head and transactions stop being mysterious.

The UTXO mental model

A UTXO (unspent transaction output) is like a banknote with a value printed on it: 12.5 DOGE, 300 DOGE, whatever it was created with. A transaction consumes whole banknotes and prints new ones:

Transaction anatomy
  inputs:   which existing UTXOs am I spending? (+ signatures proving I may)
  outputs:  new UTXOs - who gets how much
  fee:      inputs total - outputs total (implicit; miners keep it)

Because you must spend banknotes whole, almost every transaction pays change back to yourself. Send 50 DOGE using a 200 DOGE UTXO and the transaction has two outputs: 50 to the recipient, ~149.99 back to a change address your wallet controls. This is why wallet balances briefly look wrong after sending – the change hasn't confirmed yet.

Fees: priced per kilobyte, not per amount

Sending 1 DOGE and sending 1 million DOGE can cost the same fee. Fees are priced by transaction size in bytes, because block space is the scarce resource. A transaction with many inputs (lots of small banknotes) is physically bigger and costs more than one spending a single large input.

Since the 1.14.4 release lowered fee defaults, typical recommended fees are around 0.01 DOGE per kilobyte, with a dust threshold (smallest useful output) around 0.01 DOGE. A normal one-input-two-output transaction is a few hundred bytes – well under one DOGE in fees. Don't hard-code these numbers: ask your node at runtime.

$ dogecoin-cli getnetworkinfo   # look at "relayfee"
$ dogecoin-cli estimatefee 6    # fee rate targeting ~6 blocks

Dogecoin Core's wallet handles coin selection, change, and fee calculation for you when you use sendtoaddress. You only manage UTXOs by hand when building raw transactions (createrawtransaction → signrawtransaction → sendrawtransaction) – a power tool you'll rarely need in this curriculum, but now you know what it's doing.

Confirmations: how long is "final"?

A transaction in the mempool (zero confirmations) is a promise, not a payment – it can still be replaced or dropped. Each block mined on top adds one confirmation and makes reversal exponentially harder. Dogecoin's one-minute blocks mean confirmations arrive fast, and merge-mined Scrypt hashrate makes deep reorganizations expensive.

Working guidance used across this curriculum:

The pattern to remember: credit on confirmations, deliver on more confirmations, and scale the wait to what you lose if it reverses.

Two more facts that save debugging hours

• Dogecoin uses legacy Bitcoin-style transactions. No SegWit, no Taproot, no bech32 addresses. If a Bitcoin library or tutorial mentions those, that part does not apply to Dogecoin.
• OP_RETURN outputs let a transaction carry a small data payload. Useful for anchoring hashes or receipts on-chain; not a file system. Keep payloads tiny and expect the standard relay rules to limit size.