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 , ]5 [ z+ {. w+ Zfrom 35% to 42% of gross income. / f3 B: h' R( [. O3 I4 ]GDSR(gross debt service ratio)=(payment of principal and interest on mortgage+property taxes+heating costs+50% of condominium fees)/gross income.