I was working with a collection agency last year regarding a past due account around $5000. I wasn't able to pay anything at that moment, but had agreed to work out something in several months (informally). Since then it has been sent to a different collection agency. I just received a letter stating I now owe $10000 on that same account, itemized as $5000 principle and $4900 assigned interest. I find this hard to believe because just 9 months ago it was 5000 with one agency, it moved to another agency and its now $11000. I had no warning of interest charges, this letter was my first communication with this company. I am just curious if collection agencies are allowed to charge interest on accounts for which they haven't notified the consumer. Any advice on how to pursue this situation? I have contacted the company and they say it is 'assigned interest', whatever that is. Any help is much appreciated.