I will be obtaining a non-immigrant 'O' visa for voluntary work. The visa is for 90 days unless it's a multi-entry visa but I understand you have to exit the country and return for a further 90 days and so on. Is it possible to obtain a single entry 'O' visa and get an extension for another month without leaving the country i.e. get an extension at an immigration office. I want to stay for four months total.

The only extension you can get is 7 days. Unless you can meet the requirements for a 1 year extension.

Edited September 6, 200916 yr by ubonjoe

Unless they help you with a work permit and you stay with the rganisation the full 4 months, you are not going to get an extension for 1 month.

Best is to get a tourist visa when the non-O expires, or simplyy fly out to a neighbouring country and fly back again. But first I would try the multiple non-O. I believe you are British, so I would try the consulate in Hull and explain your situation.