Many lenders started offering "Flex Loans" where you can get part of your credit limit as a loan, or pay a charge off over time, with the intent that whatever fee is associated with the loan, or pay over time feature, is distinct from regular charges that appear on the same card. AMEX is great with this, I've used Chase also from time to time. Decided to try a Citi Flex Loan in August, got the advance, no issues. Shows up with an intended interest rate and payment plan. Regular charges are paid without incurring new interest costs.
The complication comes in, that Citi also, frequently, offers "Lower APR on spend" for a time period. So if you spend during the offer period, your carrying interest cost can be less than what your regular card APR is. I had activated one of these earlier in 2025, even though my autopayment does not allow the balances to accumulate, it was there on my account with a 9.99% rate.
The Flex Plan, added in August, is 10.99% APR.
What happens in this situation is, your regular charges are now in a lower APR situation than the Flex Plan. So even though the autopay is tallying up all the new charges, and the minimum / plan payment for the Flex Plan, all those payments are going to the higher APR first, meaning they are going to the Flex Plan first, not your regular charges. So now, over the past two months, Citi is re-sorting all the items, and will be "catching up" the charges that were in the 9.99% bucket, which I presumed were already being paid. So at the end of this payment, the Flex Plan will be about half the starting amount it was in August, and should start going forward and the intended monthly payment. My regular Citi charges will be at a higher APR, so will be paying off, actually, each month, since they are in a higher APR bucket.
So, if you intend to use a Flex Pay (or other pay over time mechanism) keep in mind the basic application of how payments go: Always to the higher APR charges first, before they start working on the lower APR charges. Particularly with Citi (and this was not disclosed at the time I did the Flex Plan, even though their systems should know both are in effect) don't accept a lower APR offer along with it. There's no real impact for me, since the Flex Pay went into cash, but it's annoying af. Cheers!
