I discovered that a customer who should have received a discount on the first month has been receiving the discount on subsequent months, too. The customer is paying by PayPal subscription, and there have been no problems or issues.
Would you correct the bill at this point, or leave it alone?

It depends, will it annoy him and cause him to leave? If its a huge discount each month then I suggest you correct it and maybe give him a free month or domain for the inconvenience. Also I think you should find out how the glitch happened and make sure you fix it.

Thanks, Dave. It's a one-dollar discount on a 5.99 package. It seems to have happened in the CE-Paypal subscription interface.

If it is only a $1 discount I would leave it be. I would not risk the chance of loosing a customer!

I would probably leave it, but maybe the customer wouldn’t care about paying an extra $1 if he was getting a free month. You will also earn the revenue from the free month in the long run when you add up all the $ he will be paying

Personally, if it's not the customers fault, I'd probably just leave it be.

For customer service reasons, we always eat any errors on our or our software's part. As this was NOT a customer's error, we would just let them keep their discount. A dollar isn't worth any negative publicity or hurt feelings you may get. We're talking $12 a year. Not a real big deal in the scheme of things for a business, but that $12 could cost a lot of hard feelings on the part of a customer, even for such a small amount.

For customer service reasons, we always eat any errors on our or our software's part. As this was NOT a customer's error, we would just let them keep their discount. A dollar isn't worth any negative publicity or hurt feelings you may get. We're talking $12 a year. Not a real big deal in the scheme of things for a business, but that $12 could cost a lot of hard feelings on the part of a customer, even for such a small amount.
Couldn't have said it better myself!

4/5 years ago had AOL dialup. They didnt bill me for one month by accident. Half a year later they double billed the card, once for the current month and once for the time they missed months earlier.
To be honest it pissed me off a little. If there had been 10,000 dial up providors like there seem to be web hosts, I would have left Pronto

This was obviously something that was set-up wrong on your site so I would see this as your fault, myself I wouldn't charge them for what they 'owe' but state to them what has happened and that they would need to re-subscribe to the fixed price. Maybe offer them something for the next month to sweeten them ;D

I'd say leave it at the price its currently at, you may in the future drop your prices at some point and then it'll all even out.

Same policy here. Any errors in the customers favor the customer keeps. I don't think it is fair to penalize the customer for our mistake.
There was one time a glitch caused around $3000 to be lost during the first quarter. It was a good learning experience.

You have a customer that pays on-time and doesn't call with questions every other day? Keep them! lol.

If it's just $1, I would just leave the customer alone. Bugging them over $1 could possibly anger them and make them leave. Plus, it sounds like this person has been sticking with you guys for a few months so no need to pester him.

Thanks, everyone. I think the consensus is pretty clear! :)

TBH i cant believe that this question came up, the customer pays on time each month, doesnt plague you with support issues, isnt using up loads of resources (assumption based on lack of mentioning)!!! I would leave this well alone, at the end of the day, is $12 a year really worth the bad press that you will get if you change it? And anyways, the fault was that with your system, nothing that the customer did.

I would just leave it its not worth losing the client over $1 a month.