Do I declare the amount of money received or the amount of my invoices in a time period

Dremont

9 Dec 2017 at 21:29 · Viewed 1110 times

I pay my social contributions 4 times a year. What exactly do I declare? I assume it is the value of all the invoices I have given in the three months concerned.
If this is true what happens if the invoice is not paid or there is a delay? I could end up paying tax on money not received.
I am a personne a la service and bill my customers at an hourly rate however I may not write an invoice for several weeks after the work is carried out.

Answered