Citizens of other countries (a)

If you are a citizen of one of the following countries (a):
Andorra, Argentina, Australia, Brazil, Brunei, Canada, Chile, Costa Rica, Croatia, El Salvador, Guatemala, Honduras, Hong Kong SAR Passport Holders, Israel, Japan, Korea (South Korea), Malaysia, Mexico, Monaco, New Zealand, Nicaragua, Panama, Paraguay, San Marino, Singapore, Special Adminstrative Regions of the People's Republic of China, Uruguay, USA, Vatican City State, Venezuela.

You may enter the Republic of Latvia without a visa and reside for 90 days within a 6 months period. If duration of your  stay will exceed 90 days, you will need a residence permit.  
Before the submission of the documents for a residence permit, within a month after your arrival, RTU will approve an invitation at the Office of Citizenship and Migration Affairs Foreigners Service Centre (OCMA) or at a regional division.
After the call has been confirmed, you should submit the following documents to the OCMA by presenting a valid travel document:
NOTE: The documents for your residence permit application can be submitted in Latvian, English, French, Russian or German.

NOTE: Certification of document authenticity (legalisation) is not a notarial act. Unless there are international agreements in force that provide for a different procedure, all documents issued in other countries have to be legalized. Legalisation - Certification of Document Authenticity .Certification of document authenticity (legalisation) means verification of signature and seal of a document. It is performed by a Consular Officer in order the documents drawn up in one country were in force in another one. Legalisation also implies confirmation of the legal status and authority of the signatory.

Please find more information on legalization http://www.mfa.gov.lv/en/service/legalisation/
 
Documents verifying your financial situation and notices issued by the State Revenue Agency are valid for three months since the date of issue; other documents, notices and letters, except for documents issued by the General Register Office, courts, archives or educational establishments, are valid for six months since the date of issue.