When you transfer American Express Membership Rewards points to Delta SkyMiles, Amex charges an "Excise Tax Offset Fee" of $0.0006 per point. This is a federal excise tax that Amex passes on to the consumer for transfers to domestic U.S. airlines. For a transfer of 10,000 points, the fee would be $6.00; for a maximum transfer, the fee is capped at $99. You have the option to pay this fee in cash (via your credit card statement) or by using a small portion of your Membership Rewards points, though paying in cash is generally considered a better value. As of 2026, this remains one of the few "hidden" costs of the Amex ecosystem, as transfers to international partners like British Airways or Emirates do not incur this specific fee. Note that the transfer ratio remains a standard 1:1, and most transfers occur near-instantly through the Amex website or app.