networkn: Well I went back to him nicely and he gave me a very pointed reply that the amount was outstanding, so now I have gone from mildly miffed to quite annoyed. I will pay it, but I am not as happy about it, and he will unlikely get any more work from me for his attitude.

It's one thing if you make a mistake, it's another if you get annoyed that someone raised the issue.

mattwnz:

networkn: Well I went back to him nicely and he gave me a very pointed reply that the amount was outstanding, so now I have gone from mildly miffed to quite annoyed. I will pay it, but I am not as happy about it, and he will unlikely get any more work from me for his attitude.

It's one thing if you make a mistake, it's another if you get annoyed that someone raised the issue.

Are you sure he didn't invoice you a long time ago, but you never got it? And they then never chased it up?
 The other thing is, did you follow it up all that time ago, when you didn't get any invoice? I have had two jobs done for me, which I was never invoiced for, one I can't remember the contractor I used, so can't get in contact with them, and the other I have contacted them twice for the invoice so I could pay it, and they said it would be sent next time they do the account, and the invoice never arrived. Both over 3 years ago, and pressume that they will never send it.
I would ask them to supply a price breakdown, and you don't want to be paying todays hourly rates on a job that was done years ago at a different rate.
I must admit, I have delayed invoicing people for a few years, but only for amounts under $50 where it wasn't worth the effort, and I would just add it on when I do the next job. But for $600, I would have invoiced within a month.

nickrout: Set up an automatic payment for $2.50 per week or something silly like that.

IAAL and there are some times when this just happens. The poster who referred to the lawyer who charged for a fallen through contract is very typical. Sometimes the current case (in court next week/settling house purchase tomorrow/client in crisis today/urgent domestic violence issues etc etc etc) take priority over charging a file that is finished.

A practice I developed years ago, call the client. Look at your time and expenses. "Hey I have been thinking hard about the bill for successfully suing X. My time recording shows 8 hours at $200, but I am entitled to charge for urgency, the good result, and the fact that it was very important to you (you kept calling me in the weekend!). I could justify a bill of 2,500, but I value your business and I want to keep you as a client, how does $1,950 sound?"

Half the time they say "Hell I was expecting about $3,000, send me a bill for $1,950 and I'll pay it by return. Thanks. By the way I was talking to Jim the other day and he has a similar problem...".

At which point I think "Damn I pitched that too low...", but I have kept a client who may have a $10,000 job next year and several acquaintances with work in my area of expertise. I also have $1950 that might otherwise take ages to collect.

If your tradesman had said "Hey it was a really busy time when I did that last job for you and I lost your details over Xmas and never got round to billing you. It was an out of hours callout on Xmas Eve and its double time. I could justify a bill of $600, but I'd never have billed you if you hadn't called me back. You obviously liked my work and I want your work next time you need me, let's call it $500" - you'd have paid him by now, his overdraft would be $500 less and he'd have a customer for life.

Now the sod is gonna get $2.50 per week LOL.