Most expats to Sri Lanka have their Visas organised by their employers, and this is by far the easiest way to gain entry. Volunteer organisations and NGOs also can sponsor or arrange their staff’s visas.
However, if you are attempting to organise your own visa here is the rundown. You can apply for either a Visitor’s Visa (tourist or business) or a Residence Visa. A visitor’s visa is the most easily available and is the only department in Sri Lanka that accepts electronic forms! The application process is really straightforward and can be accessed through the Tourism Board’s website. The Visitor Visa is supposed to have a 24-hour turnaround but by all accounts, it can be 7 – 14 days before you get your visa. Visitor’s visas are valid for 30 days from entry, you can extend your visa for another 6 months by visiting the Department of Immigration & Emigration, Colombo.
Residence visas are a bit more tricky, there are multiple categories: employment, investors, clergymen, students, registered Indians, ex-Sri Lankans & children, and family of a Sri Lankan. If you are interested in moving to the country, more than likely you will need to have arranged a job here first. The “employment” category is then further sub-categorized: bank employees, NGO volunteers, employees of diplomatic missions in Sri Lanka and private company employees. Details of which forms and documents you need are detailed on the immigration website. Visas are generally granted for a 1-year term, which can be annually renewed. Visa fees are detailed in a separate section of the website, but these should be checked before payment. Resident visas must be processed at a Sri Lankan mission (an embassy, high commission etc. on overseas soil), a Visitor Visa can’t be converted into a Residence Visa.
If you are lucky enough to have to visit the Department of Immigration & Emigration, rejoice in the efficiency of the Sri Lankan government. My advice would be to download the required form from their website and pre-fill before arriving, otherwise, you may need to line up twice. And if you can be up early in the AM, arriving before they open can save you untold hours of lining up and being shuffled from one desk to another.
Lastly I have to say: remember that laws in Sri Lanka are prone to change with little notice, so always double check!