«He admits to having been lying» or «he admits to have been lying»?

[Spamous]

Why is it correct to write «he admits to having been lying», but not «he admits to have been lying»? (Perhaps the context is relevant.)

 

[BobK]

Why is it correct to write «he admits to having been lying», but not «he admits to have been lying»? (Perhaps the context is relevant.)

You admit to a noun (falsehood, bad faith, unreliability, untruthfulness, inaccuracy...). You can replace the noun with a gerund: 'he admits to being economical with the truth'. ;-)

But it's more likely that an everyday speaker wouldn't use a gerund, but would just say 'he admits that he lied' (or, depending on context, 'he admitted that he'd lied'.

b

 

[Raymott]

Why is it correct to write «he admits to having been lying», but not «he admits to have been lying»? (Perhaps the context is relevant.)

As Bob says, you need a noun or gerund.
All of these use a gerund and are correct:
1. He admits to lying.
2. He admits to having lied.
3. He admits to having been lying.
While 3. is correct, it wouldn't be used often. But since you want a progressive form in the past, you could say 3, or 4.
3. He admits that he had been lying.

Your other form, "*he admits to have been lying" is wrong because of the requirements of: admit to, confess to.

With some verbs you can use this structure:
He pretends to have been lying.
He claims to have been lying.
In these cases, we can't use the form of sentence 1. *He pretends to lying, so we can't use 2 or 3 either.