Is it permissible, from a Sharia perspective, to benefit from a 55% tax exemption granted by the tax authority for saving money for 10 years, knowing that the saved money includes usurious interest, but there is no intention to benefit from it (the interest), rather only from the tax privilege?

Usury (Riba) is one of the gravest major sins. The Messenger of Allah (peace be upon him) cursed the one who consumes usury, the one who feeds it, its scribe, and its two witnesses, stating that they are all equal. The aforementioned savings account is a usurious contract that is impermissible to enter into voluntarily, even with the intention of getting rid of theurious interest, because that does not permit engaging in usury.