Despite the fact that solvency approach, i.e. public sector balance approach is most frequently used as a method of assessment of borrowing policy, the application of that approach causes a number of technical obstacles. The basic obstacle is that this approach implies selection of a long-term real interest rate and a long-term real output growth rate, as well as the forecast of future primary deficits (Masson, 1985). Besides, the sustainability criterion which requires that debt growth rate should be lower than the interest rate, can also be satisfied if the share of the debt in the output grows, as in a case when the output growth rate is