> ## Documentation Index
> Fetch the complete documentation index at: https://voltaire.tevm.sh/llms.txt
> Use this file to discover all available pages before exploring further.

# EIP-1559 Transactions

> Dynamic fee market transactions (Type 2)

<Card title="Try it Live" icon="play" href="https://playground.tevm.sh?example=primitives/transaction.ts">
  Run Transaction examples in the interactive playground
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# EIP-1559 Transactions

Dynamic fee market transactions with base fee and priority fee, introduced in London hard fork.

## Overview

EIP-1559 transactions (Type 2) replace fixed gas price with dynamic fee market. Users specify `maxFeePerGas` and `maxPriorityFeePerGas`, with actual fee determined by block's base fee.

## Type Definition

```typescript theme={null}
type EIP1559 = {
  type: Type.EIP1559      // 0x02
  chainId: bigint
  nonce: bigint
  maxPriorityFeePerGas: bigint  // Tip to miner
  maxFeePerGas: bigint          // Maximum total fee
  gasLimit: bigint
  to: AddressType | null
  value: bigint
  data: Uint8Array
  accessList: AccessList
  yParity: number         // 0 or 1
  r: Uint8Array           // 32 bytes
  s: Uint8Array           // 32 bytes
}
```

Source: [types.ts:92-109](https://github.com/evmts/voltaire/blob/main/src/primitives/Transaction/types.ts#L92-L109)

## Creating EIP-1559 Transactions

```typescript theme={null}
import * as Transaction from 'tevm/Transaction'

const tx: Transaction.EIP1559 = {
  type: Transaction.Type.EIP1559,
  chainId: 1n,
  nonce: 0n,
  maxPriorityFeePerGas: 2000000000n,  // 2 gwei tip
  maxFeePerGas: 30000000000n,         // 30 gwei max
  gasLimit: 21000n,
  to: recipientAddress,
  value: 1000000000000000000n,  // 1 ETH
  data: new Uint8Array(),
  accessList: [],
  yParity: 0,
  r: signatureR,
  s: signatureS,
}
```

## Fee Market Mechanics

### Base Fee

Block base fee adjusts based on block fullness:

* Block > 50% full: base fee increases
* Block \< 50% full: base fee decreases
* Maximum 12.5% change per block

### Effective Gas Price

```typescript theme={null}
effectiveGasPrice = baseFee + min(maxPriorityFeePerGas, maxFeePerGas - baseFee)
```

**Examples:**

```typescript theme={null}
// Case 1: Normal case
baseFee = 15 gwei
maxPriorityFeePerGas = 2 gwei
maxFeePerGas = 30 gwei
// effectiveGasPrice = 15 + min(2, 30 - 15) = 15 + 2 = 17 gwei

// Case 2: maxFeePerGas too low
baseFee = 15 gwei
maxPriorityFeePerGas = 5 gwei
maxFeePerGas = 18 gwei
// effectiveGasPrice = 15 + min(5, 18 - 15) = 15 + 3 = 18 gwei

// Case 3: maxFeePerGas = baseFee
baseFee = 20 gwei
maxPriorityFeePerGas = 2 gwei
maxFeePerGas = 20 gwei
// effectiveGasPrice = 20 + min(2, 20 - 20) = 20 + 0 = 20 gwei
```

## getEffectiveGasPrice

Calculate effective gas price given base fee.

```typescript theme={null}
function getEffectiveGasPrice(
  tx: BrandedTransactionEIP1559,
  baseFee: bigint
): bigint
```

### Usage

```typescript theme={null}
import { EIP1559 } from 'tevm/Transaction'

const tx: Transaction.EIP1559 = {
  maxPriorityFeePerGas: 2000000000n,
  maxFeePerGas: 30000000000n,
  // ...
}

const baseFee = 15000000000n  // From block header
const effectivePrice = EIP1559.getEffectiveGasPrice(tx, baseFee)
console.log(effectivePrice)  // 17000000000n (17 gwei)

// Total cost
const totalCost = effectivePrice * gasUsed + tx.value
```

Source: [EIP1559/getEffectiveGasPrice.js:13-18](https://github.com/evmts/voltaire/blob/main/src/primitives/Transaction/EIP1559/getEffectiveGasPrice.js#L13-L18)

## Fee Estimation

### Setting maxFeePerGas

Rule of thumb: `maxFeePerGas = baseFee * 2 + maxPriorityFeePerGas`

```typescript theme={null}
async function estimateFees(provider) {
  const block = await provider.getBlock('latest')
  const baseFee = block.baseFeePerGas

  return {
    maxFeePerGas: baseFee * 2n + 2000000000n,
    maxPriorityFeePerGas: 2000000000n  // 2 gwei tip
  }
}
```

### Aggressive vs Conservative

```typescript theme={null}
// Aggressive (fast inclusion)
const aggressive = {
  maxPriorityFeePerGas: 3000000000n,  // 3 gwei
  maxFeePerGas: baseFee * 2n + 3000000000n
}

// Conservative (cheaper, slower)
const conservative = {
  maxPriorityFeePerGas: 1000000000n,  // 1 gwei
  maxFeePerGas: baseFee + 5000000000n  // baseFee + 5 gwei buffer
}
```

## Gas Cost Calculation

```typescript theme={null}
// Maximum possible cost
const maxCost = tx.maxFeePerGas * tx.gasLimit + tx.value

// Actual cost (after execution)
const actualCost = effectiveGasPrice * gasUsed + tx.value

// Refund
const refund = (tx.maxFeePerGas - effectiveGasPrice) * gasUsed
```

## RLP Encoding

```
0x02 || rlp([chainId, nonce, maxPriorityFeePerGas, maxFeePerGas, gasLimit, to, value, data, accessList, yParity, r, s])
```

## Methods

```typescript theme={null}
import { EIP1559 } from 'tevm/Transaction'

// Serialization
const bytes = EIP1559.serialize(eip1559Tx)
const decoded = EIP1559.deserialize(bytes)

// Hashing
const txHash = EIP1559.hash(eip1559Tx)
const signingHash = EIP1559.getSigningHash(eip1559Tx)

// Signing
const sender = EIP1559.getSender(eip1559Tx)
const isValid = EIP1559.verifySignature(eip1559Tx)

// Gas price
const effectivePrice = EIP1559.getEffectiveGasPrice(eip1559Tx, baseFee)
```

## Benefits

1. **Predictable pricing** - Base fee makes fees more predictable
2. **Better UX** - Users specify maximum, pay actual
3. **Faster confirmation** - Priority fee for faster inclusion
4. **ETH burn** - Base fee burned, reduces ETH supply
5. **Less overpaying** - Only pay what's needed

## When to Use

Use EIP-1559 for:

* Ethereum mainnet (London+)
* Modern L2s with EIP-1559 support
* Applications needing predictable fees

**Prefer Legacy/EIP-2930** for:

* Networks without EIP-1559
* Specific gas price requirements

## EIP Reference

* [EIP-1559: Fee market change for ETH 1.0 chain](https://eips.ethereum.org/EIPS/eip-1559)