Will you tell me whether the following sentence is correct
'I as well as he am to be blamed'
I was told it's wrong and we are supposed to use 'have to be blamed'
thank you
You need the plural form of the verb, so:

"He as well as I are to be blamed"

which is the same as:

"He and I are to be blamed"

You could also use "have" such as:

"He and I have to be blamed"

but the meaning is a little different. "Are to" is like "will" and "have to" is like "must".

Edit: Putting he before I is just convention.
Dengler's Lessons and Exercises in English copyright 1914 disagrees. "If the subjects are connected by 'as well as,' 'and also,' 'and too,' 'with,' 'in addition to,' the verb must agree with the first; as, 'I, as well as he, am a student.'"