Tax Engine Overview

@dtax/tax-engine is a TypeScript-first, zero-dependency library for crypto tax calculation.

Features

23 exchange parsers — auto-detect or manually specify format
8 cost-basis methods — FIFO, LIFO, HIFO, Specific ID, and more
Transaction types — Buy, Sell, Trade, Staking, Mining, Airdrop, NFT, DeFi, Fees
Report generation — Form 8949 (CSV/PDF/TXF), Schedule D summary
Wash sale detection — flags 30-day repurchase rule violations
Deduplication — content-fingerprint based duplicate detection

Core functions

Function	Description
`parseCsv(csv, options?)`	Parse an exchange CSV into normalized transactions
`computeGains(txs, options)`	Compute capital gains for a tax year
`compareAllMethods(txs, year)`	Compare gains across all 7 comparable methods
`generateForm8949Csv(disposals, options)`	Export Form 8949 as CSV
`generateTxfFile(disposals, options)`	Export TXF file for tax software

TypeScript types

type CsvFormat =
  | 'coinbase' | 'binance' | 'binance_us' | 'kraken' | 'gemini'
  | 'crypto_com' | 'kucoin' | 'okx' | 'bybit' | 'gate' | 'bitget'
  | 'mexc' | 'htx' | 'etherscan' | 'etherscan_erc20'
  | 'solscan' | 'solscan_defi' | 'bitfinex' | 'poloniex'
  | 'koinly' | 'cointracker' | 'cryptact' | 'generic';

type CostBasisMethod =
  | 'FIFO' | 'LIFO' | 'HIFO' | 'SPECIFIC_ID'
  | 'GERMANY_FIFO' | 'PMPA' | 'TOTAL_AVERAGE' | 'UK_SHARE_POOLING';

interface ParsedTransaction {
  type: TransactionType;
  timestamp: string;        // ISO 8601
  sentAsset?: string;
  sentAmount?: number;
  receivedAsset?: string;
  receivedAmount?: number;
  feeAsset?: string;
  feeAmount?: number;
  notes?: string;
}