TDSR(Total debt service ratio)=(payment of principal and interest on mortgage+property tax +heating costs+50% of condominium fees+payments on other personal loan)/grss income. TDSR guidelines Currently range + {) s& X5 _4 e# U [, \5 Lfrom 35% to 42% of gross income. x4 L& F) W( D3 E M$ G4 k1 `% qGDSR(gross debt service ratio)=(payment of principal and interest on mortgage+property taxes+heating costs+50% of condominium fees)/gross income.