|From Elecciones en Peru|
All Peruvian citizens living in Peru are required by law to vote; it's compulsory. If you don't vote, you will be fined. Another law concerning voting is Ley Seca, which forbids the sale of alcohol shortly before and after elections.
I think that by requiring people to vote, making the sale of alcohol illegal, and having short and long-term proof of voting, Peru is trying to cut down on corruption and become more transparent.
Changing your address
You MUST vote in the district that is reflected on your DNI. Many people don't bother changing their DNI because it's such a pain to do so. This means that if you live in Lima but your DNI has an address for Arequipa, you will have to travel back to Arequipa to vote. Transportation companies really take advantage of this and jack up their prices.
I highly recommend you change your DNI to reflect your new address so you won't get fined. It usually takes about 3 months to change addresses and they cannot be done about 4 months before any election or 1 month after any election.
There are exceptions to being fined such as illness, death of a family member, loss of your DNI, natural disasters, and more. ONPE has a complete list of the exceptions. If you're a miembro de mesa you will have to pay more than those who aren't. Different areas of Peru will pay less depending on whether they are classified as a poor area or not. Elecciones en Peru also has more info about different fees for fines. For the October 2014 Elections the maximum fines were S/. 76.
Here is the website to find out if you have any fines. You can also find the form here. There is a guide on YouTube showing you how to check if you have fines. Terra also has a guide telling you how to check if you have fines.
If you live abroad, you don't have to vote, but if you are a miembro de mesa you will have to participate in the elections or get fined. Currently for those living abroad the fines can be up to $64.
Proof of voting
There are two things that Peru does to prove that you have voted: one is short-term and one is long-term. The day of the elections you're going to see people with ink on their index fingers. This is done in order to prevent double voting.
You will also be given a hologram sticker that will be put on the back of your DNI as proof of voting (sufragio). If you are fined, you will have to go to the Banco de la Nacion en Peru and pay the fine. Someone can pay the fine on your behalf if you give them your DNI. They will not give that person a sticker though. The sticker can only be given to the person whose fine is being paid.
I've heard that some embassies and consulates may allow you to pay the fine there. Someone told me that you can do this at the New York Consulate. I know the Seoul embassy will not allow you to pay. Without the sticker on the back of your DNI, legally you are not able to use it for any transactions in Peru, such as at the bank, at a notary, etc so it's best to pay the fines. Every once in a while they're forgiven, but it's no guaranteed.
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