CHANGING FROM SARLU TO MICRO – WHEN TO DECLARE AND CHANGING FROM MSA

My husband’s business (originally a SARL and now a SARLU) is closing at the end of August as we have moved department and he is changing his business type. Our accountant is dealing with the closure of the SARLU which is a Landscaping gardening business affiliated with the MSA and still registered in our old department 31.  My husband is going to start his new business towards the end of September (running courses and workshops in gardening and horticultural consulting) from our new home (Dept 11) and has decided to set up as an AE as it will be simpler to manage and the costs will be lower. 

1. I have a number of questions, but I’ll start off with when should he declare and set up his new AE business? Should he start the process now or wait until the SARLU has ceased trading (officially 31/08/2022)? 

2. I’m a little concerned about potential difficulties with changing from MSA to whatever it is that he’ll be under as an AE.  Do you think there is likely to be any problem with changing caisse and how will this affect his health and pension rights?  He is 60 in January and has been affiliated with the MSA since 2006 (with a brief change to RSI in 2009/10).

3. He also has some health issues (the main reason for closing and changing his business), so the continuation of health coverage is a concern.

Many thanks for any advice.