Invoice customization

We have got a following problem:

some clients pay advance payments; how do we add that in the invoice, subtracting from the total and having the balance at the bottom?

Once you created an invoice you should Edit it:

Add new line to your invoice:

When you add a new line to your invoice:

You can select or type percentage, or enter a fixed amount and enter description of the line:

That's how simple it can be done.

All the best