This will cost the typical autonomo or sole-trader around €250 per month. This will entitle a self-employed person to receive health care from the Portuguese national health service as well as a pension upon reaching the statutory pensionable age.
Depending on the amount paid, a sole-trader may also receive unemployment benefits should their business become unsustainable. However, this is a complex issue and eligibility will depend on how the business became unsustainable. The amount and quantity of unemployment payments will depend on the number and amount of social security contributions that have been made.
If you are under 30 years of age or have been long term unemployed or are a woman over the prescribed age you may be entitled to a reduction in the monthly payments. This needs to be checked in each particular case.
The payment falls due regardless of whether or how much you are earning from your business. It is paid monthly and so it is not sensible to register on the last day of the month as you will be liable for that months social security contributions even though you are only registered for a single day.