diff --git a/spec/System/TestSkills_spec.lua b/spec/System/TestSkills_spec.lua
index 69b21f4677..345187f53a 100644
--- a/spec/System/TestSkills_spec.lua
+++ b/spec/System/TestSkills_spec.lua
@@ -216,6 +216,42 @@ describe("TestAttacks", function()
 		assert.True(math.abs(finalCost - 12) < 0.1) -- floor(12 * 1.5) / 1.5
 	end)
 
+	it("Test flat cost is added before cost efficiency", function()
+		-- In-game order is ((base cost * multipliers) + flat cost) / (1 + cost efficiency)
+		build.skillsTab:PasteSocketGroup("Hydrosphere 1/0  1\n")
+
+		-- Hydrosphere 12 base mana cost
+		build.configTab.input.customMods = "+10 to Total Mana Cost\n50% increased Mana Cost Efficiency"
+		build.configTab:BuildModList()
+		runCallback("OnFrame")
+
+		local finalCost = build.calcsTab.mainOutput.ManaCost
+		-- (12 + 10) / 1.5 = 14.667
+		assert.True(math.abs(finalCost - 22 / 1.5) < 0.001)
+	end)
+	it("Test flat cost is added before cost efficiency for life costs", function()
+		build.skillsTab:PasteSocketGroup("Hydrosphere 1/0  1\n")
+
+		-- Convert Hydrosphere's 12 base cost to life, then add +10 flat and 50% efficiency
+		build.configTab.input.customMods = "Skills Cost Life instead of Mana\n+10 to Total Cost\n50% increased Cost Efficiency"
+		build.configTab:BuildModList()
+		runCallback("OnFrame")
+
+		-- (12 + 10) / 1.5 = 14.667
+		assert.True(math.abs(build.calcsTab.mainOutput.LifeCost - 22 / 1.5) < 0.001)
+	end)
+
+	it("Test flat cost is added before cost efficiency for energy shield costs (#10003)", function()
+		build.skillsTab:PasteSocketGroup("Hydrosphere 1/0  1\n")
+
+		-- Convert Hydrosphere's 12 base cost to ES, then add +10 flat and 50% efficiency
+		build.configTab.input.customMods = "Skills Cost Energy Shield instead of Mana or Life\n+10 to Total Cost\n50% increased Cost Efficiency"
+		build.configTab:BuildModList()
+		runCallback("OnFrame")
+
+		-- (12 + 10) / 1.5 = 14.667
+		assert.True(math.abs(build.calcsTab.mainOutput.ESCost - 22 / 1.5) < 0.001)
+	end)
 	it("Test mana cost efficiency with support gems", function()
 		-- Test interaction between cost efficiency and cost multipliers
 		build.skillsTab:PasteSocketGroup("Contagion 6/0  1\nMagnified Area I 1/0  1")
diff --git a/src/Modules/CalcOffence.lua b/src/Modules/CalcOffence.lua
index 85ecb9f772..956ac30db3 100644
--- a/src/Modules/CalcOffence.lua
+++ b/src/Modules/CalcOffence.lua
@@ -1756,7 +1756,7 @@ function calcs.offence(env, actor, activeSkill)
 				moreType = skillModList:More(skillCfg, val.type.."Cost")
 				moreCost = skillModList:More(skillCfg, "Cost")
 				inc = skillModList:Sum("INC", skillCfg, val.type.."Cost", "Cost")
-				output[costNameRaw] = val.baseCostRaw and m_max(0, m_max(0, (1 + inc / 100) * val.baseCostRaw * moreType * moreCost / costEfficiency) + val.totalCost)
+				output[costNameRaw] = val.baseCostRaw and m_max(0, m_max(0, (1 + inc / 100) * val.baseCostRaw * moreType * moreCost) + val.totalCost) / costEfficiency
 				if inc < 0 then
 					output[costName] = m_max(0, m_ceil((1 + inc / 100) * output[costName]))
 				else
@@ -1772,9 +1772,9 @@ function calcs.offence(env, actor, activeSkill)
 				else
 					output[costName] = m_max(0, m_floor(moreCost * output[costName]))
 				end
+				output[costName] = m_max(0, output[costName] + val.totalCost)
 				-- Apply cost efficiency (similar to reservation efficiency)
 				output[costName] = m_max(0, output[costName] / costEfficiency)
-				output[costName] = m_max(0, output[costName] + val.totalCost)
 				if val.type == "Mana" and hybridLifeCost > 0 then -- Life/Mana Mastery
 					output[costName] = m_max(0, m_floor((1 - hybridLifeCost) * output[costName]))
 					output[costNameRaw] = output[costNameRaw] and m_max(0, (1 - hybridLifeCost) * output[costNameRaw])
@@ -1785,10 +1785,10 @@ function calcs.offence(env, actor, activeSkill)
 				output[costName] = m_floor(val.baseCost + val.baseCostNoMult)
 				output[costName] = m_max(0, (1 + inc / 100) * output[costName])
 				output[costName] = m_max(0, moreType * output[costName])
+				output[costName] = m_max(0, output[costName] + val.totalCost)
 				-- Apply cost efficiency for unaffected costs too
 				output[costName] = m_max(0, output[costName] / costEfficiency)
-				output[costName] = m_max(0, output[costName] + val.totalCost)
-				output[costNameRaw] = val.baseCostRaw and m_max(0, m_max(0, (1 + inc / 100) * (val.baseCostRaw + val.baseCostNoMult) * moreType / costEfficiency) + val.totalCost)
+				output[costNameRaw] = val.baseCostRaw and m_max(0, m_max(0, (1 + inc / 100) * (val.baseCostRaw + val.baseCostNoMult) * moreType) + val.totalCost) / costEfficiency
 			end
 			if breakdown and hasCost then
 				breakdown[costName] = {
@@ -1815,16 +1815,16 @@ function calcs.offence(env, actor, activeSkill)
 				if moreType ~= 1 then
 					t_insert(breakdown[costName], s_format("x %.2f ^8(more/less "..val.text.." cost)", moreType))
 				end
+				if val.totalCost ~= 0 then
+					t_insert(breakdown[costName], s_format("%+d ^8(total " .. val.text .. " cost)", val.totalCost))
+				end
 				if costEfficiency ~= 1 then
 					t_insert(breakdown[costName], s_format("/ %.2f ^8(" .. val.text .. " cost efficiency)", costEfficiency))
 				end
-				if val.totalCost ~= 0 then
-					t_insert(breakdown[costName], s_format("%+d ^8(total "..val.text.." cost)", val.totalCost))
-				end
 				if val.type == "Mana" and hybridLifeCost > 0 then
 					t_insert(breakdown[costName], s_format("x %.2f ^8(%d%% paid for with life)", (1-hybridLifeCost), hybridLifeCost*100))
 				end
-				t_insert(breakdown[costName], s_format("= %"..(val.upfront and "d" or ".2f")..(val.percent and "%%" or ""), output[costName]))
+				t_insert(breakdown[costName], s_format("= %" .. (val.upfront and "d" or ".2f") .. (val.percent and "%%" or ""), m_ceil(output[costName])))
 			end
 		end
 	end
diff --git a/src/Modules/CalcSections.lua b/src/Modules/CalcSections.lua
index 0dc6da8a03..fcc1f55f16 100644
--- a/src/Modules/CalcSections.lua
+++ b/src/Modules/CalcSections.lua
@@ -40,6 +40,18 @@ local fireConvert = {
 	"FireDamageConvertToChaos", "ElementalDamageConvertToChaos", "NonChaosDamageConvertToChaos", 
 	"FireDamageGainAsChaos", "ElementalDamageGainAsChaos", "NonChaosDamageGainAsChaos"
 }
+local manaCost = {
+	"ManaCost", "Cost", "ManaCostNoMult", "ManaCostEfficiency", "CostEfficiency"
+}
+local lifeCost = {
+	"LifeCost", "Cost", "LifeCostNoMult", "LifeCostEfficiency", "CostEfficiency"
+}
+local ESCost = {
+	"ESCost", "Cost", "ESCostNoMult", "ESCostEfficiency", "CostEfficiency"
+}
+local rageCost = {
+	"RageCost", "Cost", "RageCostNoMult", "RageCostEfficiency", "CostEfficiency"
+}
 
 -- format {width, id, group, color, subsection:{default hidden, label, data:{}}}
 return {
@@ -619,20 +631,20 @@ return {
 { 1, "SkillTypeStats", 1, colorCodes.OFFENCE, {{ defaultCollapsed = false, label = "Skill type-specific Stats", data = {
 	{ label = "Gem Level", haveOutput = "GemHasLevel", { format = "{0:output:GemLevel}", { breakdown = "GemLevel" }, { modName = { "GemLevel" }, cfg = "skill" },{ modName = { "GemSupportLevel" }, cfg = "skill" }, { modName = { "GemItemLevel" }, cfg = "skill" }, }, },
 	{ label = "Gem Quality", haveOutput = "GemHasQuality", { format = "{0:output:GemQuality}", { breakdown = "GemQuality" }, { modName = { "GemQuality" }, cfg = "skill" },{ modName = { "GemSupportQuality" }, cfg = "skill" }, { modName = { "GemItemQuality" }, cfg = "skill" }, }, },
-	{ label = "Mana Cost", color = colorCodes.MANA, haveOutput = "ManaHasCost", { format = "{0:output:ManaCost}", { breakdown = "ManaCost" }, { modName = { "ManaCost", "Cost", "ManaCostNoMult" }, cfg = "skill" }, }, },
-	{ label = "Mana % Cost", color = colorCodes.MANA, haveOutput = "ManaPercentHasCost", { format = "{0:output:ManaPercentCost}", { breakdown = "ManaPercentCost" }, { modName = { "ManaCost", "Cost", "ManaCostNoMult" }, cfg = "skill" }, }, },
-	{ label = "Mana per second", color = colorCodes.MANA, haveOutput = "ManaPerSecondHasCost", { format = "{2:output:ManaPerSecondCost}", { breakdown = "ManaPerSecondCost" }, { modName = { "ManaCost", "Cost", "ManaCostNoMult" }, cfg = "skill" }, }, },
-	{ label = "Mana % per second", color = colorCodes.MANA, haveOutput = "ManaPercentPerSecondHasCost", { format = "{2:output:ManaPercentPerSecondCost}", { breakdown = "ManaPercentPerSecondCost" }, { modName = { "ManaCost", "Cost", "ManaCostNoMult" }, cfg = "skill" }, }, },
-	{ label = "Life Cost", color = colorCodes.LIFE, haveOutput = "LifeHasCost", { format = "{0:output:LifeCost}", { breakdown = "LifeCost" }, { modName = { "LifeCost", "Cost", "LifeCostNoMult" }, cfg = "skill" }, }, },
-	{ label = "Life % Cost", color = colorCodes.LIFE, haveOutput = "LifePercentHasCost", { format = "{0:output:LifePercentCost}", { breakdown = "LifePercentCost" }, { modName = { "LifeCost", "Cost", "LifeCostNoMult" }, cfg = "skill" }, }, },
-	{ label = "Life per second", color = colorCodes.LIFE, haveOutput = "LifePerSecondHasCost", { format = "{2:output:LifePerSecondCost}", { breakdown = "LifePerSecondCost" }, { modName = { "LifeCost", "Cost", "LifeCostNoMult" }, cfg = "skill" }, }, },
-	{ label = "Life % per second", color = colorCodes.LIFE, haveOutput = "LifePercentPerSecondHasCost", { format = "{2:output:LifePercentPerSecondCost}", { breakdown = "LifePercentPerSecondCost" }, { modName = { "LifeCost", "Cost", "LifeCostNoMult" }, cfg = "skill" }, }, },
-	{ label = "ES Cost", color = colorCodes.ES, haveOutput = "ESHasCost", { format = "{0:output:ESCost}", { breakdown = "ESCost" }, { modName = { "ESCost", "Cost", "ESCostNoMult" }, cfg = "skill" }, }, },
-	{ label = "ES per second", color = colorCodes.ES, haveOutput = "ESPerSecondHasCost", { format = "{2:output:ESPerSecondCost}", { breakdown = "ESPerSecondCost" }, { modName = { "ESCost", "Cost", "ESCostNoMult" }, cfg = "skill" }, }, },
-	{ label = "ES % per second", color = colorCodes.ES, haveOutput = "ESPercentPerSecondHasCost", { format = "{2:output:ESPercentPerSecondCost}", { breakdown = "ESPercentPerSecondCost" }, { modName = { "ESCost", "Cost", "ESCostNoMult" }, cfg = "skill" }, }, },
-	{ label = "Rage Cost", color = colorCodes.RAGE, haveOutput = "RageHasCost", { format = "{0:output:RageCost}", { breakdown = "RageCost" }, { modName = { "RageCost", "Cost", "RageNoMult" }, cfg = "skill" }, }, },
-	{ label = "Rage per second", color = colorCodes.RAGE, haveOutput = "RagePerSecondHasCost", { format = "{2:output:RagePerSecondCost}", { breakdown = "RagePerSecondCost" }, { modName = { "RageCost", "Cost", "RageNoMult" }, cfg = "skill" }, }, },
-	{ label = "Soul Cost", color = colorCodes.RAGE, haveOutput = "SoulHasCost", { format = "{0:output:SoulCost}", { breakdown = "SoulCost" }, { modName = { "SoulCost" }, cfg = "skill" }, }, },
+	{ label = "Mana Cost", color = colorCodes.MANA, haveOutput = "ManaHasCost", { format = "{0:output:ManaCost}", { breakdown = "ManaCost" }, { modName = manaCost, cfg = "skill" }, }, },
+	{ label = "Mana % Cost", color = colorCodes.MANA, haveOutput = "ManaPercentHasCost", { format = "{0:output:ManaPercentCost}", { breakdown = "ManaPercentCost" }, { modName = manaCost, cfg = "skill" }, }, },
+	{ label = "Mana per second", color = colorCodes.MANA, haveOutput = "ManaPerSecondHasCost", { format = "{2:output:ManaPerSecondCost}", { breakdown = "ManaPerSecondCost" }, { modName = manaCost, cfg = "skill" }, }, },
+	{ label = "Mana % per second", color = colorCodes.MANA, haveOutput = "ManaPercentPerSecondHasCost", { format = "{2:output:ManaPercentPerSecondCost}", { breakdown = "ManaPercentPerSecondCost" }, { modName = manaCost, cfg = "skill" }, }, },
+	{ label = "Life Cost", color = colorCodes.LIFE, haveOutput = "LifeHasCost", { format = "{0:output:LifeCost}", { breakdown = "LifeCost" }, { modName = lifeCost, cfg = "skill" }, }, },
+	{ label = "Life % Cost", color = colorCodes.LIFE, haveOutput = "LifePercentHasCost", { format = "{0:output:LifePercentCost}", { breakdown = "LifePercentCost" }, { modName = lifeCost, cfg = "skill" }, }, },
+	{ label = "Life per second", color = colorCodes.LIFE, haveOutput = "LifePerSecondHasCost", { format = "{2:output:LifePerSecondCost}", { breakdown = "LifePerSecondCost" }, { modName = lifeCost, cfg = "skill" }, }, },
+	{ label = "Life % per second", color = colorCodes.LIFE, haveOutput = "LifePercentPerSecondHasCost", { format = "{2:output:LifePercentPerSecondCost}", { breakdown = "LifePercentPerSecondCost" }, { modName = lifeCost, cfg = "skill" }, }, },
+	{ label = "ES Cost", color = colorCodes.ES, haveOutput = "ESHasCost", { format = "{0:output:ESCost}", { breakdown = "ESCost" }, { modName = ESCost, cfg = "skill" }, }, },
+	{ label = "ES per second", color = colorCodes.ES, haveOutput = "ESPerSecondHasCost", { format = "{2:output:ESPerSecondCost}", { breakdown = "ESPerSecondCost" }, { modName = ESCost, cfg = "skill" }, }, },
+	{ label = "ES % per second", color = colorCodes.ES, haveOutput = "ESPercentPerSecondHasCost", { format = "{2:output:ESPercentPerSecondCost}", { breakdown = "ESPercentPerSecondCost" }, { modName = ESCost, cfg = "skill" }, }, },
+	{ label = "Rage Cost", color = colorCodes.RAGE, haveOutput = "RageHasCost", { format = "{0:output:RageCost}", { breakdown = "RageCost" }, { modName = rageCost, cfg = "skill" }, }, },
+	{ label = "Rage per second", color = colorCodes.RAGE, haveOutput = "RagePerSecondHasCost", { format = "{2:output:RagePerSecondCost}", { breakdown = "RagePerSecondCost" }, { modName = rageCost, cfg = "skill" }, }, },
+	{ label = "Soul Cost", color = colorCodes.RAGE, haveOutput = "SoulHasCost", { format = "{0:output:SoulCost}", { breakdown = "SoulCost" }, { modName = { "SoulCost", "SoulCostEfficiency" }, cfg = "skill" }, }, },
 	{ label = "Active Minion Limit", haveOutput = "ActiveMinionLimit", { format = "{0:output:ActiveMinionLimit}" } },
 	{ label = "Quantity Multiplier", haveOutput = "QuantityMultiplier", { format = "{0:output:QuantityMultiplier}",
 	    { breakdown = "QuantityMultiplier" },