Heathcare system in Spain.

First of all I will try to explain in a general way, with my own words, because it is a bit difficut to say. There are a lot of complicated terms,
Spanish Healthcare consists of both private and Public Healthcare, with many hospitals and centres offering both private and state health services . You don't need to have a private insurance to get medical treatment in Spain, but it is usually allows you to get treatment for a non-emergency.
State Healthcare is free of charge to anyone, but the question is how can this be financed? or Where does the money come out of (<em>or</em> come from) to pay for all this?
First, a percentage is deducted of from the salary from of the worker, second there is another amount of money that is paid by the factory or institution where the worker develops does his job (<em>or</em> where the employee works), tHIRD All , Third, all these amounts are paid to the Treasury of the Social Security (TGSS), this institution acts as huge piggy bank ,from which they will take out the money to pay the healthcare,and the medical prescriptions, and to finish, there is also from TGSS takes out the rest payment of money when any Spaniard was is retired, I mean a salary called a "Pension." However in at this moment because of the crisis, all Spaniards are thinking that in the future maybe I couldn't won't have a pension. I have to add that Healthcare in Spain has been one of the best in the world...

Difficult text, well written :-)

My corrections are in red and my suggestions to sound more natural are in blue/grey.

Heathcare system in Spain.

First of all I will try to explain it in a general way, with my own words, because it is a bit difficut to say.There are a lot of complicated terms,
Spanish Healthcare consits of both private and Public Healthcare,with many hospitals and centres offering both private and state Health services . You don't need to have a private insurance to get medical treatment in Spain, but it is usually allows you get treatment for a non-emergency problem.
State Healthcare is free of charge to anyone, but the question is how can this be financed? or Where does the money come out to pay for all this?
First , a percentage is deducted out of the worker's salary, second there is another amount of money is paid by the factory or institution where the worker is employed, tHIRD All , these amounts are paid to the Treasury of the Social Security( TGSS), this institution acts as huge piggy bank ,from which  money will be taken out to pay for healthcare, including medical prescriptions, and to finish, the TGSS pays out money to retired people, sort of like a pension. However in this moment because of the crisis , all spaniards are thinking that in the future maybe I couldn't/might not have a pension. I have to add Healthcare in Spain <em>has been</em> one of the best in the world...

si la sistema todavía es buena, diríamos, ...is one of the best in the world" usa el presente simple aquí, no presente perfecto

en este momento. no decimos in ingles "in this moment", un poco raro, si correcto pero raro.

intenta "at this time"