Does the invoice you send need to contain exactly what you charged them for, item by item?
To nobody’s surprise, I would argue that supplying a detailed breakdown only makes the whole experience worse for everybody.
First, we are not talking about the grocery bill here – if my dentist charges me without divulging the exact list of material ingredients he used, I would not blink twice. Same with a lawyer, accountant, or even designer – I’m not going to understand half of it anyway, and may misunderstand the rest. losing time for us both. Yes, it’s based on trust, but that’s not new in this context.
Second, clients are not really paying for what you do, but what they get out of it – the outcome of what you do, not output. They may think that’s not true, but this example usually sets them straight: if they had a camera in my office and can see me work for 60 hours, but not get any tangible results out of it, would they recommend me to friends as good value? Probably not.
On the other hand, if they could see me wave a magic wand and get them the business results they wanted without “doing any work”, literally not spending more than a split second on it, would they recommend me to friends as good value? Most likely, yes!
Try the example yourself to show them that they don’t really care what’s on the bill, as long as what they pay is great value for what they get out of it.