FeeBumpTransaction

Represents a Fee Bump Transaction in the Stellar network.

Fee bump transactions allow you to increase the fee of a previously submitted transaction that may be stuck in the queue due to insufficient fees. This is useful when network fees spike unexpectedly or when you need to prioritize a transaction.

How Fee Bumps Work

A fee bump transaction wraps an existing transaction (the "inner transaction") and specifies a new, higher fee. The fee bump transaction has its own source account (the "fee source") which pays the additional fee. This allows a different account to sponsor the fee increase.

Important Rules

1. The inner transaction must NOT already be a fee bump transaction

2. The new fee must be higher than the inner transaction's fee

3. The inner transaction can have any number of operations (1-100)

4. The fee bump adds one additional "operation" for fee calculation purposes

5. Both the inner transaction and fee bump transaction require signatures

Fee Calculation

When using base fee (recommended):

maxFee = (baseFee × (numInnerOperations + 1)) + sorobanResourceFee

The "+1" accounts for the fee bump operation itself.

Usage Example

// Original transaction stuck due to low fee
val originalTx = TransactionBuilder(sourceAccount, Network.PUBLIC)
    .addOperation(PaymentOperation(...))
    .setBaseFee(100)
    .build()
originalTx.sign(sourceKeypair)

// Create fee bump to increase priority
val feeBump = FeeBumpTransaction.createWithBaseFee(
    feeSource = "GFEE...",  // Account paying the additional fee
    baseFee = 1000,          // New base fee (must be higher)
    innerTransaction = originalTx
)

// Sign with fee source account
feeBump.sign(feeSourceKeypair)

// Submit the fee bump transaction
horizonServer.submitTransaction(feeBump)

Network Behavior

• If the inner transaction has already been applied, the fee bump will fail

• If the inner transaction is in the queue, it will be replaced by the fee bump

• The fee source account must have sufficient balance to cover the fee increase

See also