I have just completed my first freelance project with a customer, and I am now sitting down to create the invoice.
In case it matters: Both me and the company are UK based, and I am acting as a member of a partnership (and therefore invoicing under my legal name)
The project has been a little bumpy (as I guess they always are) but everyone seems satisfied now, which is great.
I expected before starting the project that I would be working on a time + materials basis, but I ended up receiving a Purchase Order for the equivalent of the upper limit of my estimate.
As a result of various misunderstandings and miscommunications, I have ended up spending more time than my initial estimate allowed for to complete the task I was given. I am happy to accept this extra work without quibble (largely as I don't have the energy to fight over a few hours), however I would like to try and tactfully inform them that this extra work occurred and I have chosen on my own behalf not to charge them for it, in a kind of "aren't I helpful" sort of a way.
As such - I was considering including an additional line item in my invoice indicating the excess hours worked, billed at a rate of 0 per hour. Or alternatively, applying a discount equal to the extra work done.
I wanted to know if there were any possible negative consequences of this, or if it is something that is frowned upon or otherwise just "not the done thing".