Current situation

VAT is calculated from the taxable turnover at the rate of 12%
VAT for purchased goods, works and services is credited (offset) to accrued VAT

The positive difference between calculated VAT and offset VAT is payble to the budget.
Negative difference between calculated VAT and credited VAT is subject either to be returned from the budget (zero rate turnover) or credited to future payments.
Challenges

Significant budget losses on VAT due to fraudulent schemes use created by possibility of VAT amounts return (refund) from the budget
High administration costs to prevent various fraudulent schemes
Possibility of corruption in VAT administration and refund

work