When I extend a return it says on the letter that the payment date is 10/15!?

In my opinion it should never say you have until 10/15!?

Here are the rules.

Filing Extension: An extension to file grants you extra time to submit your tax return, usually until October 15th, without incurring failure-to-file penalties.

Payment Deadline Remains: The deadline for paying any taxes owed remains the original tax filing due date, typically April 15th.

Interest and Penalties: If you don't pay your taxes by the original due date, interest and penalties for late payment will be assessed, even if you have a filing extension.