VPT gap - when the fiscal value is far below the purchase price, the AT can reassess upward post-sale, permanently increasing IMI
IMT exposure - transfer tax is calculated on whichever is higher: purchase price or VPT. A gap means you owe more than you budgeted
Undeclared area - registered m² smaller than physical reality, often because extensions were added without updating the tax record
IMI arrears - unpaid annual property tax which becomes your liability at completion