I believe it was the CARD Act (maybe someone can correct me) that established that any payment OVER your minimum payment due gets applied to your highest-APR balances first (but your minimum-due will typically be applied to the lowest-APR balance). Since cash advances are typically your highest APR balance, any amount you pay over minimum due should be applied to that. IF you only pay minimum-due, it will get applied to your lowest-APR balance first (probably not your cash advance), and subsequent minimum payments will keep getting applied only to your lowest-APR balances until there aren't any left, and only then will your minimum payments go towards your high-APR cash advance balance.
So that fastest way to pay off your cash advance without getting hit with its high APR is to pay your minimum payment plus whatever amount your cash advance was for. Even if you can't pay the entire cash advance balance now, you should pay as much of it as you can.
Indeed, if you can manage paying your entire statement balance now, then your APR grace period will completely reset.
Total Loan Balance: $43k / $65k
Total SL: $78k
When your monthly paper statement is printed, there is a section on that statement which specifies how your Total Balance is allocated to various ways that you borrowed money: Regular Spend, Balance Transfers at potentially different APR and different Expiration date tranches, purchases under 0% APR situations, and Cash Advance. Each of these tranches has an average balance calculated, shows the APR applicable to that average balance, and that leads to your interest charge for the month.
Or you could pay the card balance to zero and that would about cover it. Perhaps a bit of trailing interest that you need to look for on the next printed statement.
Not sure about Discover, but each issuer does it differently. Cap1 makes the cash advance the last thing that gets paid.
Yep, as I understand, it's been that way since 2009. There is no "it varies from issuer to issuer", they have a federal law they have to abide by... and that law says that any payment amount over the minimum payment must be applied to the highest interest portion of the balance (which is, typically, the cash advance portion)