How to Track Prediction-Market P&L for Tax Season (Polymarket & Kalshi)

Target Keywords: "prediction market tax tracking", "polymarket pnl tracker", "kalshi pnl tracking", "track prediction market profit and loss"

This article is for educational and record-keeping purposes only. It is not tax, legal, or financial advice. Always consult a qualified tax professional about your specific situation before filing.

Introduction

Most people who trade prediction markets discover the same uncomfortable truth in April: the platforms didn't keep their records for them. Neither Polymarket nor Kalshi hands you a clean, broker-style tax summary, and "I'll figure it out later" turns into a weekend of squinting at transaction histories.

This is a practical, step-by-step guide to building a manual P&L record across Polymarket and Kalshi — the kind of record that makes tax season a quick handoff to your accountant rather than a reconstruction project. We'll cover what columns to keep, how to reconcile each month, and how to export everything cleanly at year-end.

Step 1: Decide on Your Columns

A good ledger answers, for every position, "what did I trade, when, and what was the net result?" Keep these columns:

Column	Example	Notes
Platform	Kalshi	So a combined record stays sortable
Date opened	2025-09-12	Start of the holding period
Date closed/resolved	2025-09-20	When the result is realized
Market / event	"CPI above 3.0% — Sept"	Plain-language description
Side	Yes	Your position direction
Contracts / shares	100	Quantity
Entry price	$0.41	Cost per unit
Exit / settlement	$1.00	What you received per unit
Fees	$0.60	Trading + settlement fees
Net result	+$58.40	Your realized P&L

The single most common mistake is omitting fees. They're small per trade and large in aggregate, and they directly affect your net numbers.

Step 2: Log Deposits and Withdrawals Separately

Your trading P&L and your cash movements are different things, and conflating them is how people end up with numbers that don't tie out. Keep a second short list:

• Deposits — money you moved onto the platform (date, amount)
• Withdrawals — money you took off (date, amount)

This matters because your account balance changes for two reasons: trades resolving and cash moving. To verify your trade record is complete, you reconcile like this:

Starting balance
+ deposits
− withdrawals
+ net trading P&L
= ending balance (should match the platform)

If it doesn't match, you've missed a trade, a fee, or a transfer — and you've caught it in minutes instead of months later.

Step 3: Adopt a Monthly Reconciliation Habit

Real-time logging is ideal but unrealistic for most people. A monthly rhythm is the sweet spot:

1. Pick a day (e.g., the first of each month) to update your ledger.
2. Enter every closed/resolved position from the prior month into your record.
3. Add the month's deposits and withdrawals.
4. Run the reconciliation above for each platform.
5. Resolve discrepancies immediately while the context is fresh, and leave a note on anything ambiguous to ask your accountant.

Twelve quick monthly sessions beat one impossible April marathon.

Step 4: Use a Manual Tracker Instead of a Raw Spreadsheet

You can do all of this in a bare spreadsheet, but a purpose-built manual tracker saves time and reduces errors. With Manage Bankroll, you record each position by hand and the running P&L is computed for you — across both Polymarket and Kalshi in one place, plus deposits and withdrawals.

A few things to know about the approach:

• It's manual by design. You type in your own numbers — there is no syncing, importing, or wallet connection. That's a feature for tax records: every figure is one you verified.
• You stay in full control. Add, edit, or delete any entry anytime.
• It's multi-platform and multi-vertical. If you also track poker, sports, or trading, it lives in the same ledger — handy when your accountant wants the full picture.

The prediction market tracker is purpose-built for this exact workflow.

Step 5: Export Cleanly for Your Accountant

When the year closes, your goal is a single, readable record you can hand off without explanation. Make sure your year-end export includes:

• A per-position list with all the columns from Step 1
• A deposits/withdrawals list
• A per-platform summary (total gains, total losses, total fees)
• Notes on anything you flagged as unclear

Hand that to a tax professional and let them determine the correct treatment. Your role ends where theirs begins — but a clean handoff saves you billable hours and reduces the chance of an error.

A Worked Example

Imagine a month with three Kalshi positions and two Polymarket positions:

• Kalshi: +$58.40, −$22.00, +$15.10 → +$51.50
• Polymarket: +$67.50, −$70.00 → −$2.50
• Fees across all five: −$4.20
• Net month P&L: +$44.80

You also deposited $200 and withdrew $100. Plugging into the reconciliation, your ending balance should be: start + 200 − 100 + 44.80. If that matches the platforms, your records are complete for the month.

Notice how the example separates three things that are easy to blur together: the gross wins, the gross losses, and the fees. Under a tax regime where loss deductibility may be limited, that separation isn't just tidy bookkeeping — it can be the difference between a return your accountant can file confidently and one built on guesses. Keeping wins, losses, and fees as distinct figures from the start means you never have to disentangle them later.

Common Mistakes That Make Tax Season Harder

A few recurring errors turn an easy handoff into a painful one. Avoid these and you're most of the way there:

• Lumping deposits in with profits. Money you transferred onto a platform is not income. Keep cash movements in their own list, always.
• Forgetting fees and gas. They feel negligible per trade but materially change your net figures across a year.
• Logging only winners. Losses are part of the record too — and under limited-deduction rules, capturing every one of them matters.
• Waiting until April. Context evaporates. By the time you try to reconstruct a market from six months ago, you may not remember the entry price or whether you closed early.
• Trusting a balance as a record. A balance is a single number at a single moment. Taxes need per-position detail with dates.

Tools to Help

• Prediction market tracker — manual P&L logging across Polymarket and Kalshi.
• Gambling & event-contract tax calculator — an educational aid for understanding the tax picture (verify with a professional).

Frequently Asked Questions

What's the easiest way to track Polymarket and Kalshi P&L for taxes?

Keep a manual ledger with consistent columns (date, market, side, quantity, entry, exit, fees, net) and reconcile monthly. A prediction market tracker automates the running math while you enter trades yourself.

Should deposits and withdrawals be in the same record as trades?

Track them separately but in the same system. Cash movements and trading P&L are different; keeping both lets you reconcile your balance and confirm your trade record is complete.

How often should I update my records?

Monthly is the realistic sweet spot. It keeps context fresh and prevents an unmanageable year-end reconstruction.

Do I need this if the platform shows my balance?

Yes. A balance is a snapshot, not a tax record. You need per-position detail with dates and fees, which platforms generally don't package for tax purposes.

The Bottom Line

Tracking prediction-market P&L for taxes isn't complicated — it's just a habit. Pick your columns, log deposits and withdrawals separately, reconcile monthly, and export cleanly. Do that with a manual, you-controlled tracker and tax season becomes a five-minute handoff. Then let a qualified professional handle the filing itself.

Related reading: Kalshi taxes 2026 guide and Polymarket taxes 2026 guide.