Mistakes on forms can lead to tax and benefits being underpaid
Government jargon should be taken more seriously, particularly as some people are missing out on benefits, MPs say.
A public administration select committee report said many pensioners did not claim benefits because of problems understanding forms.
It recommended that people encountering poorly written forms should be encouraged to make official complaints.
It suggested plain speaking should be praised more and impenetrable language "exposed and condemned".
The MPs said sketch writers "perform a public service by skewering the most egregious linguistic excesses".
In its report on its inquiry into political and administrative language, the committee said that in politics, badly worded explanations could stop people understanding how policies would work and "stock phrases" could be so overused they replaced original expression and thought.
Euphemisms such as "downsizing" or "efficiency savings" are routinely used by politicians when they mean budget or staff cuts, the report said.
The committee heard about complaints over letters from government department, which included one from a Citizens Advice Bureau adviser who pointed out: "A four-page letter to ask for a medical certificate is not helpful."
The National Audit Office said departments had to be "more realistic about how people read and complete forms rather than making assumptions about how citizens should behave".
Its own investigation into pensioner poverty found that a major reason they did not apply for all their benefits was because of "difficulty in completing forms".
And HM Revenue and Customs estimated that mistakes made when people filled in self-assessment tax forms resulted in about £300m in underpaid tax every year.
The MPs' committee said poorly worded documents were a "significant concern, especially when large numbers of people are affected".
"Long, complex official forms, officious letters and confusing requests for information can all deter individuals from attempting to deal with public authorities," the report said.
"This is particularly worrying when it prevents people from getting the benefits or services to which they are entitled."
People should be encouraged to complain about particularly bad cases of official language - first to the department concerned, then to the relevant ombudsman, it added.
Poorly worded forms which stopped people understanding their rights amount to "maladministration", the committee said - which would provide grounds for a complaint to an ombudsman.
Committee chairman Tony Wright said: "Good government requires good language, while bad language is a sign of poor government. Far too often, government uses language that obscures, confuses or evades.
"We propose that cases of bad official language should be treated as 'maladministration', as for any other type of poor administration.
"Complaints made on this basis must be dealt with properly. This would help ensure that government takes seriously its responsibility to use good, clear and understandable language."