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 / L4 { P. ]/ Y' E8 w y, u' qfrom 35% to 42% of gross income. ) ]5 n! E5 y2 u1 d) O/ A7 u6 dGDSR(gross debt service ratio)=(payment of principal and interest on mortgage+property taxes+heating costs+50% of condominium fees)/gross income.