diff --git a/modules/45_carbonprice/NDC2018/postsolve.gms b/modules/45_carbonprice/NDC2018/postsolve.gms
index 5a270c1891f425be77faed371368415ded827b1b..739cb3d2953b6423015ed0746b1d74c3707fa4fc 100644
--- a/modules/45_carbonprice/NDC2018/postsolve.gms
+++ b/modules/45_carbonprice/NDC2018/postsolve.gms
@@ -86,7 +86,8 @@ pm_taxCO2eq(ttot,regi)$(ttot.val gt 2030) = max(pm_taxCO2eq(ttot,regi),1*sm_DptC
 *#' exception for China to meet the target of 2030 peak: linear increase starts already in 2025
 pm_taxCO2eq(ttot,regi)$(ttot.val gt 2025 AND (sameas(regi,"CHN") OR sameas(regi,"CHA"))) = max(pm_taxCO2eq(ttot,regi),1*sm_DptCO2_2_TDpGtC * (1+(ttot.val-2025)*9/7));
 
-
+*** new 2020 carbon price definition: weighted average of 2015 and 2025, with triple weight for 2015 (which is zero for all non-eu regions).
+pm_taxCO2eq("2020",regi) = (3*pm_taxCO2eq("2015",regi)+pm_taxCO2eq("2025",regi))/4;
 
 ***
 ******special treatment for 2020 (not relevant if cm_startyear for NDC scenario is 2020, but relevant if earlier)
diff --git a/modules/45_carbonprice/NDC2018/preloop.gms b/modules/45_carbonprice/NDC2018/preloop.gms
index b4c383980bb80f8b4eff823d170a6061c23000cb..e8e04342050c67188fa8cfcbe438b6e6542d2197 100644
--- a/modules/45_carbonprice/NDC2018/preloop.gms
+++ b/modules/45_carbonprice/NDC2018/preloop.gms
@@ -19,6 +19,9 @@ pm_taxCO2eq(ttot,regi)$(ttot.val gt 2030) = max(pm_taxCO2eq(ttot,regi),1*sm_DptC
 *** exception for China to meet the target of 2030 peak: linear increase starts already in 2025
 pm_taxCO2eq(ttot,regi)$(ttot.val gt 2025 AND (sameas(regi,"CHN") OR sameas(regi,"CHA"))) = max(pm_taxCO2eq(ttot,regi),1*sm_DptCO2_2_TDpGtC * (1+(ttot.val-2025)*9/7));
 
+*** new 2020 carbon price definition: weighted average of 2015 and 2025, with triple weight for 2015 (which is zero for all non-eu regions).
+pm_taxCO2eq("2020",regi) = (3*pm_taxCO2eq("2015",regi)+pm_taxCO2eq("2025",regi))/4;
+
 
 *#' @equations 
 *#'  calculate level of emission target that it should converge to, two types of targets