Plain language and clear standard language are different things. Plain language is easier to use and understand than clear standard language. Both support the integration of a person who has moved to Finland and help them understand official communications.
Plain language supports foreign-language speakers who have moved to Finland, especially in the early stages of integration and language learning. Even at a later stage, it is important that a person who does not speak Finnish or Swedish as their mother tongue receives official information in at least clear standard language. These days, more official communications are available in plain language, thereby also supporting those who have lived in Finland for a longer time.
Language comprehension matters: clear standard language and plain language make it easier for immigrants to live independently, go to school and work. Language is also essentially related to the accessibility of services.
You should also pay attention to the clarity of spoken language. Plain language can be spoken or written. In addition to plain Finnish, you can speak and write plain Swedish (lättläst svenska) in Finland.
The authorities are responsible for good standards of official language
According to the Administrative Procedure Act (434/2003, section 9), the authority must use language that is clear, easy to understand and to the point. Official language is the language used for official duties. Good official language has many benefits, both for the authorities and for their customers and partners.