The scheme permits investors to buy the shares from foreign companies. (Change Voice)

Under the scheme, the investors are permitted to buy shares from foreign companies

Under the scheme, the investors may be permitted to buy shares from foreign companies

Under the scheme, the investors have been permitted to buy shares from foreign companies

Under the scheme, the investors were permitted to buy shares from foreign companies.

None of these

The scheme permits investors to buy the shares from foreign companies (Present Indefinite Tense)

Under the scheme, the investors are permitted to buy shares from foreign companies. (Passive)

We use is,am, are with Present Indefinite Tense in Passive Voice.

***