When it comes to operating businesses overseas, clients are often wrong about how their businesses should be classified and income reported for US tax purposes.  Getting these wrong can have detrimental effect on your client's tax liability and could toll the SOL.  If you haven't already, you may like to ask a few more questions of your client (P.S. how an entity is classified legally and for tax purposes in the country of formation is not relevant under the IRC).

For a high level technical discussion about social security and overseas business, you may also like to take a look at this thread: https://proconnect.intuit.com/community/proseries-tax-discussions/discussion/i-have-a-self-employed-...

As far as input is concerned, you will need to do the following:

1. Create a F.2555 and make all the relevant entries provided your client is eligible for FEIE;
2. Create a Sch C, make all the usual input for income, expenses, etc.; and
3. On the Sch C you created with step #2, click on the Less Common Scenario tab and link it to the F.2555 you created in step #1.