What-If Scenarios
Trying to decide whether to sell now or wait? Upload your CSVs, type the trade you are considering, and we replay your full ledger with the hypothetical added. See the realised gain, the long vs short-term split, the tax owed at your bracket, and which specific lots FIFO would eat - before the order leaves your wallet.
1. Upload your transactions
Add up to 5 CSV files and pick the matching exchange for each. We replay your entire ledger so the simulation is accurate even when an old lot is involved.
2. Tax assumptions
3. The trade you are considering
The simulation appends a single hypothetical transaction to the end of your ledger and re-runs FIFO. The original CSVs are never modified.
Before vs after this trade
| Metric | Before | After | Delta |
|---|
Lots this sale would consume
FIFO eats the oldest lots first. These are the exact lots from your upload that would be matched against the simulated sale, in order.
| Asset | Acquired | Disposed | Term | Qty | Cost basis | Proceeds | Gain / loss |
|---|
Notes
Why simulate before you sell?
FIFO cost-basis matching is order-dependent. The lot that gets eaten by your next sale is whichever one you bought first - even if you remember buying at a much lower price last week. The "live in your head" estimate of your tax bill is almost always wrong, often by enough to change the trade.
The What-If simulator runs the same FIFO engine that powers the Crypto Tax Calculator. The numbers you see here are the numbers that will appear on your tax return next April if you execute the trade as described. The estimated tax figure uses the marginal rate you supply; for US users with mixed long and short-term lots, the long portion is taxed at preferential rates and the short portion as ordinary income.
Common uses:
- Year-end harvesting - check whether selling a specific lot at a loss covers the gain you already realised.
- Long-term threshold check - find out if waiting 30 more days flips a sale from short-term to long-term.
- Partial sale sizing - dial the quantity until the realised gain hits the bracket boundary you want.
- Re-entry planning - simulate a buy at a lower price to see what the new average basis becomes.