I am a freelancer. Last year I did a large project for a client. The job went very well. However at the end of the project things were quite hectic with me wrapping up the project and starting a new job for a different customer at the same time.
The client was very happy with the work I did. This year they have brought me back in to work on a new project. However while I was preparing the invoice for the new work, I discovered I had made a big mistake. I never invoiced them for the final block of work last year! It's not a few hours either - its almost 3 weeks of work that I never billed them for!
As far as I can see there are 3 options for how this could work:
They should pay the full amount. The fact that I was almost 12 months late in sending them an invoice is irrelevant.
They should pay, but perhaps only partially, or at a steep discount. Perhaps paying 50% of the original amount.
Failing to invoice them was absolutely my mistake and I should just write this up as a painful lesson in keeping on top of my paperwork and move on.
What do people think the right thing is to do?
To provide some more details:
The original project went well! Everyone was happy with the outcome and there is no dispute that the work was done and done well.
The amount of work I forgot to invoice for was almost a 3rd of the total project. This would obviously have an impact on their financial metrics for how the project went.
The company is a fairly small one. They should be able to pay, but its definitely going to have an impact on their financial planning, etc.
They never warned me that I hadn't sent an invoice. I'm sure this was not deliberate on their part.
I have a very good relationship with the customer and they show every sign of being decent human beings. Its very likely that I would continue to pick up future work from them, be introduced to new clients by them, etc.