Tax and Accounting Tooling for Prediction Market Traders

Build tax and accounting products for prediction market traders with the Bravado Data API tax statement endpoints.

The problem

Prediction-market gains and losses need to be reported to tax authorities in most jurisdictions. On Polymarket, that means reconstructing every disposition (sale, merge, redemption) with cost basis and proceeds, over an entire tax year, and producing a document a preparer can hand to the tax authority. Wallet-level exports from Polymarket’s UI do not contain the required fields.

What Bravado provides

• Tax reports via GET /traders/{address}/tax-report with per-disposition detail and summary totals.
• R1 statements via GET /traders/{address}/statements/r1 for standalone access to disposition rows without the parent wrapper.
• Reconciliation statements via GET /traders/{address}/reconciliation cross-checking Bravado’s computed balance against on-chain state.
• PMWAS methodology documented in PnL methodology so a preparer can verify the numbers.

APIs used

API	What a tax workflow uses it for
Data API	R1 dispositions, per-year tax reports, and the R8 reconciliation certificate
UMA API	Resolution dates, which determine when a gain or loss is realised

Worked example

Generate a year-end statement CSV for a client wallet:

import os, requests, csv

API = "https://bravado-api-k7kaq.ondigitalocean.app"
H = {"Authorization": f"Bearer {os.environ['BRAVADO_API_KEY']}"}

def fetch_r1(addr, year):
    rows, offset = [], 0
    while True:
        r = requests.get(
            f"{API}/traders/{addr}/statements/r1",
            params={"year": year, "limit": 1000, "offset": offset},
            headers=H,
        ).json()
        rows.extend(r["dispositions"])
        if not r["has_more"]:
            return rows
        offset += 1000

def to_csv(rows, path):
    fields = [
        "acquired_at", "disposed_at", "proceeds", "cost_basis",
        "realized_pnl", "hold_period", "market_id", "outcome",
    ]
    with open(path, "w", newline="") as f:
        w = csv.DictWriter(f, fieldnames=fields)
        w.writeheader()
        for row in rows:
            w.writerow({k: row[k] for k in fields})

rows = fetch_r1("0xabc...", 2025)
to_csv(rows, "client_2025_dispositions.csv")
print(f"Exported {len(rows)} dispositions")

Each row has enough detail to file a Form 8949-style report.

Product patterns

• Turbotax-style import. Serve dispositions as CSV in the format a specific tax software ingests.
• CPA workflow. Bulk download for a portfolio of client wallets.
• Live tax dashboard. Show projected year-to-date liability with per-market drill-down.

Verifying the numbers

Every disposition returned by the API can be reconstructed from the underlying fills using the PMWAS methodology. If a client’s preparer disputes a number, cross-check by pulling the raw fills from GET /traders/{address}/trades and applying the standard.

Bravado provides accounting data, not tax advice. Confirm the correct treatment of prediction-market gains and losses in your jurisdiction with a qualified tax professional.

Related

• Guide: Generate a US tax statement
• Data API: PMWAS accounting
• Analytics: tax report endpoint