Open the API keys page by clicking the settings icon and clicking API Keys.
Click the Create New Key button.
Enter your two-factor authentication code if necessary.
Confirm the new API key from the verification email you receive from Poloniex.
Back on Poloniex, deselect the Enable Trading and Enable Withdrawals checkboxes of the new API key.
Paste your API key and secret to TokenTax.
Instructions for U.S. filers (as Poloniex has shut down for U.S. customers)
You will see a page that says "Withdraw funds to avoid fees" and below that, a link to their FAQ. Click through to the FAQ.
Scroll down to see instructions for "How do I download my history for taxes?" and follow the instructions, and be sure to download the CSV for trade activity.
If you are not a U.S. user: