Clarification auto-entrepreneur and non profit association income

We had a conversation a while ago about my situation and I am still a little confused. My questions were regarding payment and whether it is best to be paid by an association or as an auto-entrepreneur.

The situation is: I work as an auto-entrepreneur and I also work for an Association.  In the past I have always invoiced the Association as an auto-entrepreneur and then they have paid me.  However, this year, my auto-entrepreneur work is doing really well.  I will earn around the 35,000€ alone.  However, I am doing lots of hours for the association and need to invoice this money somehow.  The association is happy to either pay me with cheque emploi associative, or continue the same way as before, where I invoice them and they then pay.  However, if they give me a work contract CDD, they would pay me a lower rate in order to cost in the fact of having to pay tax. 

So, my question is what is the best for both parties, myself and the association?

• If they pay me with auto-entrepreneur, it will be around 15,000€  but then I will have to pay the TVA, which you said in your previous correspondance, I think about a 45% tax on this.
• If they pay me with a work contract CDD, how much tax would they have to pay on what they pay me?

Which is the best way of getting paid for me please?

Also, some of the links you sent didn’t work in your previous correspondance.  There was one for info-retraite and there was one that you said I could calculate my retraite, but when I tried to it said that this was unavailable for auto-entrepreneurs.
Thanks for your response.
Hannah