You don't "merge" the accounts into one entity; rather, you link them to enable the transfer of points. In 2026, the process is done through the American Express website. Log in to your Amex account, navigate to "Rewards & Benefits," and select "Transfer Points." Choose Delta SkyMiles from the list of travel partners. You will be prompted to enter your 10-digit Delta SkyMiles number. It is critical that the name on your American Express account exactly matches the name on your Delta account (e.g., if one has a middle initial and the other doesn't, the link might fail). Once linked, you can transfer Membership Rewards points to SkyMiles at a 1,000 to 1,000 ratio (increments of 500). In 2026, these transfers are almost instantaneous, usually taking less than 10 minutes. Note that there is a small "Federal Excise Tax Offset Fee" (approx. $0.0006 per point, capped at $99) charged by Amex for transfers to U.S. domestic airlines like Delta, which will be billed to your credit card statement.