Turn broker data into trusted tax intelligence.
Import a supported CSV, review flagged rows, confirm a locked snapshot, then prepare France 2025 tax figures with deterministic, explainable calculations.
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The Problem
Broker statements are non-standardized messy data nightmares.
Inconsistent CSV layouts
Each broker exports different columns, dates, and number formats. TaxGain currently accepts one documented CSV layout; additional adapters can be added later.
Multi-Currency & Stock Splits
Calculating cost basis across foreign currencies, withholding taxes, and corporate actions manually leads to tax calculation errors.
Lack of Auditability
Generic spreadsheets lack an immutable record of raw line data versus human modifications, leaving investors vulnerable to tax audits.
The Solution
TaxGain · AI Advisor: Intelligent Transaction Normalization Engine
We bridge raw broker data and tax-preparation requirements with automated parsing, AI-assisted anomaly detection, and human verification.
Supported CSV ingestion
Upload a standard broker CSV export. TaxGain detects the supported layout automatically. PDF/OCR ingest is planned.
Standard transaction categories
Normalizes trades into standard BUY, SELL, DIVIDEND, CASH_FEE, and CORPORATE_ACTION events.
AI Anomaly & Review Detection
Flags unmapped tickers, low-confidence parses, or missing FX exchange rates before locking.
Human-in-the-Loop Audit
Review flagged transactions row-by-row with side-by-side raw broker line comparison.
France weighted-average cost (PMP)
Calculates securities capital gains with the French weighted-average (PMP) method — not US FIFO/LIFO lots.
Tax-preparation package
Maps confirmed activity to France 2025 boxes and a signature-ready preparation PDF. TaxGain helps prepare tax filing packages. It does not file your taxes for you.
Step-by-Step Workflow
5 steps from broker CSV to tax preparation
Upload Statement
Select portfolio and drag-and-drop CSV broker file.
Parse & Normalize
Engine converts lines into standard event schema.
Review Uncertain Rows
Investor validates flagged or ambiguous rows.
Confirm & Lock
Lock validated statement for downstream calculations.
Analyze & Export
Generate a France tax-preparation summary from confirmed activity.
Product Preview
Built for serious investors preparing French taxes
Illustrative preview — sample values only, not live portfolio data
| Date | Type | Ticker | Quantity | Price | Total | Status |
|---|---|---|---|---|---|---|
| 2024-01-15 | Buy | AAPL | 10 | $185.50 | $1,855.00 | Valid |
| 2024-03-15 | Buy | UNKNOWN_TICKER | 50 | $12.40 | $620.00 | Needs Review |
| 2024-04-02 | Sell | NVDA | 2 | $890.00 | $1,780.00 | Valid |
AI Boundaries & Deterministic Math
We separate AI parsing from tax math. Large Language Models and fuzzy rules are ONLY used to parse messy CSV descriptions and propose symbol mappings. Acquisition cost, realized gain or loss, and FX conversions use strict deterministic code — French PMP, not FIFO.
Immutable Auditability
Every raw line from your uploaded broker statement is preserved permanently in its original form. When you confirm or edit a transaction, TaxGain stores an immutable audit log linking the investor decision to the raw row.
Ready to turn a supported broker CSV into tax-preparation figures?
Create an account, import a supported CSV, confirm the statement, then prepare France 2025 tax figures in Tax Center. TaxGain does not submit your declaration to DGFiP.