As a Permanente Resident, are working papers needed?

Just wondering what happens as a resident permanent relative to working papers.
If we do some type of business or consulting, or whatever, do we still need to get working papers?

Thanks,

No papers from INM, but you must inform them -- not permission, just information.

Then I assume if you are 'working', then you must owe taxes on something and the government will want you to charge the IVA if you are a small business person.

As life goes on!

Yes but no if you fit under the Regimen de Incorporacion Fiscal guidelines where there is a 100% tax credit the first year, 90% second year, etc.

gracias, as always.