As a starting point, it is necessary that you get access for the webpage of the chilean taxes office, and to do so you need to identify yourself as a new taxpayer by obtaining a username and a password at the website www.sii.cl.
Follow these steps in the website:
"Identificar nuevo contribuyente" > "Obtención de clave secreta" > "Ingresar Rut"
(identify new taxpayer > Obtain a secret password > Type your chilean ID number)
Then it is necessary to obtain a bank account. See more information in the Moving to Chile section of this webpage.
If you emit a payment receipt ("Boleta de Honorarios") once a month you have to pay the 10% of the total as tax, depending on the type of receipt you give (ask for more details). So, if you are receiving 100% of your salary (and not 90%), it means you are not paying taxes and need to fill the form F29 (https://www.sii.cl/IVA2000/index.html) after the month you want to declare ends, e.g. declare your July monthly income, on Aug 1st. On form F29, you need to add manually 10% of the money you received in the previous month in field 152 and then validate the form. After doing that, you will be directed to a payment page. Please ask someone else to help you on the first time you do this, since the details of how to do it online may change with time.
Besides monthly declarations of your incomes, it is absolutely necessary that you complete an annual declaration that will allow you to recover part or all the money that you have been paying as taxes, on the subsequent year. This process can be realized completely on line (filling up the F22 form), and the money will be returned to your bank account by two or three months after, if your Annualy Income Declaration is accepted. The process for online declaration starts around Apr 1st of the following year you want to declare, e.g. for your annual income of 2013 fill the form from Apr 1st of 2014.
The F22 form is a bit complicated but it can be automatically filled. To avoid complications and errors choose the automatic filling option. If the money amounts look right after the automatic form is generated, add your bank account information to receive your money. If your form is rejected, the SII webpage will notice you and you will have to try again, but this situation is very rare, so do not worry.
If you forget to fill any of this forms (F29 and F22) you will be fined, although you don't always need to fill F29 (if your receive 90% of your salary), that is why is very important to be organized about this matter. F22 is very important, don't forget about it.
To obtain your username and password in the SII page, follow these steps. If the following process shows an error please go to any SII offices for obtaining them (http://www.sii.cl/sobre_el_sii/oficinas/rm.htm).