They probably have a very good idea. That being said I suspect this could be a mechanism to "verify" or confirm things are still accurate or current from what

They probably have a very good idea. That being said I suspect this could be a mechanism to "verify" or confirm things are still accurate or current from what you last said it was. Imagine you telling your CC company you make 250k a year to get a higher limit but only make 100k. Perhaps that credit card account has a large amount of cash flow due to expenses being refunded from an employer or something. A way to find that out could be to ask you to update what you make every so often hoping you'll do the "math" wrong. If it's a CC company they might also just want to give you a higher credit limit - it's how they make money after all!