I have maintenance deals with almost 100% of my clients (either with a monthly fee or a by-the-hour agreement). The only time I don't charge is when the error o

I have maintenance deals with almost 100% of my clients (either with a monthly fee or a by-the-hour agreement). The only time I don't charge is when the error or problem is a direct result of something I've done. I have an industry specific suite of content management systems and utilities so typically a mistake found by one client is a problem for them all. Not charging for fixing your own mistakes helps generate a little goodwill.