I'll wager it's higher than you thought. Interest rates on most credit cards have been going up. They're usually pegged to the bank prime lending rate. The prime rate has risen to 9.5 percent, up 1.75 percentage points in the past 19 months. Combining the two would give you a credit card rate of 17.5 percent today.
Many banks change their credit card rates quarterly.
The prime rose 0.5 percentage point in May, so July may be the first time you see that increase on your bill. But small rate increases are only for good boys and girls. The new rate applies not just to your new debt but also to the debt you already have. It's socked to people who've made three late payments within a six-month period, or are more than 60 days late on a single bill. It's hard to get a good, new card with slow-pay on your record.