diff --git a/src/App.tsx b/src/App.tsx
index 80730d4..80e0e79 100644
--- a/src/App.tsx
+++ b/src/App.tsx
@@ -20,6 +20,9 @@ const INITIAL_PROFILE: UserProfile = {
   age: 65, // Retirement Start Age
   baseAge: 55, // Current Age
   filingStatus: FilingStatus.Single,
+  spouseAge: 0,
+  spouseSocialSecurity: 0,
+  spouseSocialSecurityStartAge: 67,
   spendingNeed: 60000,
   isSpendingReal: true,
   assets: { traditionalIRA: 250000, rothIRA: 100000, rothBasis: 50000, brokerage: 150000, hsa: 25000 },
diff --git a/src/components/features/InputSection.tsx b/src/components/features/InputSection.tsx
index 778dac5..9e7fd0a 100644
--- a/src/components/features/InputSection.tsx
+++ b/src/components/features/InputSection.tsx
@@ -190,18 +190,57 @@ const InputSection: React.FC<InputSectionProps> = ({ profile, setProfile, onRest
               placeholder="Target Age"
             />
           </div>
-          <div>
+          <div className="md:col-span-2">
             <label htmlFor="filingStatus" className={labelClass}>Filing Status</label>
             <select
               id="filingStatus"
               value={profile.filingStatus}
-              onChange={(e) => handleChange('filingStatus', e.target.value)}
+              onChange={(e) => {
+                const newStatus = e.target.value as FilingStatus;
+                if (newStatus === FilingStatus.Single) {
+                  setProfile({
+                    ...profile,
+                    filingStatus: newStatus,
+                    spouseAge: 0,
+                    spouseSocialSecurity: 0,
+                    spouseSocialSecurityStartAge: 67,
+                  });
+                } else {
+                  setProfile({
+                    ...profile,
+                    filingStatus: newStatus,
+                    spouseAge: profile.spouseAge || 65,
+                    spouseSocialSecurity: profile.spouseSocialSecurity || 24000,
+                    spouseSocialSecurityStartAge: profile.spouseSocialSecurityStartAge || 67,
+                  });
+                }
+              }}
               className={inputClass}
             >
               <option value={FilingStatus.Single}>Single</option>
               <option value={FilingStatus.MarriedJoint}>Married Filing Jointly</option>
             </select>
           </div>
+          {profile.filingStatus === FilingStatus.MarriedJoint && (
+            <div className="md:col-span-2">
+              <label htmlFor="spouseAge" className={labelClass}>
+                Partner's Retirement Age
+                <Tooltip content="Your partner's age when you begin retirement. Used for the age-65+ deduction — each person 65+ gets an extra deduction." />
+              </label>
+              <input
+                id="spouseAge"
+                type="number"
+                value={profile.spouseAge || 65}
+                onChange={(e) => {
+                  const rawValue = e.target.value;
+                  const updatedValue = rawValue === '' ? 65 : parseInt(rawValue, 10);
+                  handleChange('spouseAge', updatedValue);
+                }}
+                className={inputClass}
+                placeholder="65"
+              />
+            </div>
+          )}
           <div className="md:col-span-2">
             <div className="flex items-center justify-between mb-1">
               <label htmlFor="spendingNeed" className="text-sm font-medium text-slate-600 dark:text-slate-300 flex items-center gap-1">
@@ -317,7 +356,9 @@ const InputSection: React.FC<InputSectionProps> = ({ profile, setProfile, onRest
         </h2>
         <div className="grid grid-cols-1 md:grid-cols-2 gap-4">
           <div>
-            <label htmlFor="socialSecurity" className={labelClass}>Social Security Benefit</label>
+            <label htmlFor="socialSecurity" className={labelClass}>
+              {profile.filingStatus === FilingStatus.MarriedJoint ? 'Your SS Benefit' : 'Social Security Benefit'}
+            </label>
             <div className="relative">
               <span className={iconClass}>$</span>
               <FormattedNumberInput
@@ -329,7 +370,9 @@ const InputSection: React.FC<InputSectionProps> = ({ profile, setProfile, onRest
             </div>
           </div>
           <div>
-            <label htmlFor="ssStartAge" className={labelClass}>SS Start Age</label>
+            <label htmlFor="ssStartAge" className={labelClass}>
+              {profile.filingStatus === FilingStatus.MarriedJoint ? 'Your SS Start Age' : 'SS Start Age'}
+            </label>
             <div className="relative">
               <input
                 id="ssStartAge"
@@ -340,6 +383,36 @@ const InputSection: React.FC<InputSectionProps> = ({ profile, setProfile, onRest
               />
             </div>
           </div>
+          {profile.filingStatus === FilingStatus.MarriedJoint && (
+            <>
+              <div>
+                <label htmlFor="spouseSS" className={labelClass}>
+                  Partner SS Benefit
+                  <Tooltip content="Partner's expected annual Social Security benefit. Enter the annual amount." />
+                </label>
+                <div className="relative">
+                  <span className={iconClass}>$</span>
+                  <FormattedNumberInput
+                    id="spouseSS"
+                    value={profile.spouseSocialSecurity || 0}
+                    onChange={(val) => handleChange('spouseSocialSecurity', val)}
+                    className={`${inputClass} pl-8`}
+                  />
+                </div>
+              </div>
+              <div>
+                <label htmlFor="spouseSSAge" className={labelClass}>Partner SS Start Age</label>
+                <input
+                  id="spouseSSAge"
+                  type="number"
+                  value={profile.spouseSocialSecurityStartAge || 67}
+                  onChange={(e) => handleChange('spouseSocialSecurityStartAge', parseInt(e.target.value) || 67)}
+                  className={inputClass}
+                  placeholder="67"
+                />
+              </div>
+            </>
+          )}
           <div className="md:col-span-2">
             <label htmlFor="pension" className={labelClass}>Pension / Annuity</label>
             <div className="relative">
diff --git a/src/components/features/wizard/Steps/Step6Income.tsx b/src/components/features/wizard/Steps/Step6Income.tsx
index e045e6e..c09d47f 100644
--- a/src/components/features/wizard/Steps/Step6Income.tsx
+++ b/src/components/features/wizard/Steps/Step6Income.tsx
@@ -1,6 +1,7 @@
 import React from 'react';
 import { WizardState } from '../types';
-import { Activity, DollarSign } from 'lucide-react';
+import { FilingStatus } from '../../../../types';
+import { Activity, DollarSign, Users } from 'lucide-react';
 
 interface CheckProps {
     data: WizardState;
@@ -9,7 +10,7 @@ interface CheckProps {
 
 const Step6Income: React.FC<CheckProps> = ({ data, update }) => {
     // Ensure futureIncome object exists
-    const income = data.futureIncome || { socialSecurity: 0, socialSecurityStartAge: 62, pension: 0 };
+    const income = data.futureIncome || { socialSecurity: 0, socialSecurityStartAge: 62, pension: 0, spouseSocialSecurity: 0, spouseSocialSecurityStartAge: 67 };
 
     // Local state for formatted inputs
     // Initialize monthly SS display by dividing annual amount by 12
@@ -20,6 +21,16 @@ const Step6Income: React.FC<CheckProps> = ({ data, update }) => {
     const [ssStartAgeDisplay, setSsStartAgeDisplay] = React.useState((income.socialSecurityStartAge || 62).toString());
     const [pensionDisplay, setPensionDisplay] = React.useState((income.pension || 0).toLocaleString());
 
+    // Spouse SS display states
+    const [spouseSSDisplay, setSpouseSSDisplay] = React.useState(
+        income.spouseSocialSecurity ? Math.round((income.spouseSocialSecurity || 0) / 12).toLocaleString() : '0'
+    );
+    const [spouseSSStartAgeDisplay, setSpouseSSStartAgeDisplay] = React.useState(
+        (income.spouseSocialSecurityStartAge || 67).toString()
+    );
+
+    const isMFJ = data.filingStatus === FilingStatus.MarriedJoint;
+
     const handleDisplayChange = (
         field: keyof typeof income,
         value: string,
@@ -42,8 +53,9 @@ const Step6Income: React.FC<CheckProps> = ({ data, update }) => {
 
         setter(Number(raw).toLocaleString());
 
-        // If updating Social Security, convert monthly input to annual for the state
-        const valueToSave = field === 'socialSecurity' ? Number(raw) * 12 : Number(raw);
+        // If updating Social Security (primary or spouse), convert monthly input to annual
+        const valueToSave = (field === 'socialSecurity' || field === 'spouseSocialSecurity')
+            ? Number(raw) * 12 : Number(raw);
 
         update({
             futureIncome: {
@@ -53,6 +65,8 @@ const Step6Income: React.FC<CheckProps> = ({ data, update }) => {
         });
     };
 
+    const inputClass = "w-full text-lg font-bold p-4 pl-8 rounded-xl border-slate-200 dark:border-slate-700 bg-white dark:bg-slate-800 focus:ring-2 focus:ring-purple-500 outline-none transition-all";
+
     return (
         <div className="space-y-6 animate-in slide-in-from-right duration-500">
             <div className="text-center space-y-2">
@@ -68,7 +82,7 @@ const Step6Income: React.FC<CheckProps> = ({ data, update }) => {
             <div className="max-w-md mx-auto space-y-6 pt-4">
                 <div>
                     <label className="block text-sm font-medium text-slate-700 dark:text-slate-300 mb-2">
-                        Estimated Monthly Social Security
+                        {isMFJ ? 'Your Estimated Monthly Social Security' : 'Estimated Monthly Social Security'}
                     </label>
                     <div className="relative mb-2">
                         <span className="absolute left-4 top-1/2 transform -translate-y-1/2 text-slate-400 font-bold">$</span>
@@ -76,7 +90,7 @@ const Step6Income: React.FC<CheckProps> = ({ data, update }) => {
                             type="text"
                             value={ssDisplay}
                             onChange={(e) => handleDisplayChange('socialSecurity', e.target.value, setSsDisplay)}
-                            className="w-full text-lg font-bold p-4 pl-8 rounded-xl border-slate-200 dark:border-slate-700 bg-white dark:bg-slate-800 focus:ring-2 focus:ring-purple-500 outline-none transition-all"
+                            className={inputClass}
                             placeholder="0"
                         />
                     </div>
@@ -87,7 +101,7 @@ const Step6Income: React.FC<CheckProps> = ({ data, update }) => {
 
                 <div>
                     <label className="block text-sm font-medium text-slate-700 dark:text-slate-300 mb-2">
-                        Start Age (e.g. 62, 67, 70)
+                        {isMFJ ? 'Your SS Start Age (e.g. 62, 67, 70)' : 'Start Age (e.g. 62, 67, 70)'}
                     </label>
                     <div className="relative mb-2">
                         <input
@@ -100,6 +114,45 @@ const Step6Income: React.FC<CheckProps> = ({ data, update }) => {
                     </div>
                 </div>
 
+                {/* Partner SS fields — visible only for MFJ */}
+                {isMFJ && (
+                    <div className="border-t border-slate-200 dark:border-slate-700 pt-6 space-y-4">
+                        <div className="flex items-center gap-2 mb-2">
+                            <Users className="w-4 h-4 text-purple-500" />
+                            <p className="text-sm font-bold text-purple-600 dark:text-purple-400">Partner's Social Security</p>
+                        </div>
+                        <div>
+                            <label className="block text-sm font-medium text-slate-700 dark:text-slate-300 mb-2">
+                                Partner's Monthly Social Security
+                            </label>
+                            <div className="relative mb-2">
+                                <span className="absolute left-4 top-1/2 transform -translate-y-1/2 text-slate-400 font-bold">$</span>
+                                <input
+                                    type="text"
+                                    value={spouseSSDisplay}
+                                    onChange={(e) => handleDisplayChange('spouseSocialSecurity', e.target.value, setSpouseSSDisplay)}
+                                    className={inputClass}
+                                    placeholder="0"
+                                />
+                            </div>
+                        </div>
+                        <div>
+                            <label className="block text-sm font-medium text-slate-700 dark:text-slate-300 mb-2">
+                                Partner's SS Start Age (e.g. 62, 67, 70)
+                            </label>
+                            <div className="relative mb-2">
+                                <input
+                                    type="text"
+                                    value={spouseSSStartAgeDisplay}
+                                    onChange={(e) => handleDisplayChange('spouseSocialSecurityStartAge', e.target.value, setSpouseSSStartAgeDisplay)}
+                                    className="w-full text-lg font-bold p-4 pl-4 rounded-xl border-slate-200 dark:border-slate-700 bg-white dark:bg-slate-800 focus:ring-2 focus:ring-purple-500 outline-none transition-all"
+                                    placeholder="67"
+                                />
+                            </div>
+                        </div>
+                    </div>
+                )}
+
                 <div>
                     <label className="block text-sm font-medium text-slate-700 dark:text-slate-300 mb-2">
                         Annual Pension / Annuity
@@ -110,7 +163,7 @@ const Step6Income: React.FC<CheckProps> = ({ data, update }) => {
                             type="text"
                             value={pensionDisplay}
                             onChange={(e) => handleDisplayChange('pension', e.target.value, setPensionDisplay)}
-                            className="w-full text-lg font-bold p-4 pl-8 rounded-xl border-slate-200 dark:border-slate-700 bg-white dark:bg-slate-800 focus:ring-2 focus:ring-purple-500 outline-none transition-all"
+                            className={inputClass}
                             placeholder="0"
                         />
                     </div>
diff --git a/src/components/features/wizard/Steps/Step8Results.tsx b/src/components/features/wizard/Steps/Step8Results.tsx
index e280f9f..3db7efc 100644
--- a/src/components/features/wizard/Steps/Step8Results.tsx
+++ b/src/components/features/wizard/Steps/Step8Results.tsx
@@ -14,6 +14,7 @@ interface CheckProps {
 
 const DUMMY_PROFILE: UserProfile = {
     age: 65, baseAge: 55, filingStatus: FilingStatus.Single,
+    spouseAge: 0, spouseSocialSecurity: 0, spouseSocialSecurityStartAge: 67,
     spendingNeed: 0, isSpendingReal: true,
     assets: { traditionalIRA: 0, rothIRA: 0, rothBasis: 0, brokerage: 0, hsa: 0 },
     contributions: { traditionalIRA: 0, rothIRA: 0, brokerage: 0, hsa: 0 },
diff --git a/src/components/features/wizard/WizardModal.tsx b/src/components/features/wizard/WizardModal.tsx
index bb19d56..70dcb32 100644
--- a/src/components/features/wizard/WizardModal.tsx
+++ b/src/components/features/wizard/WizardModal.tsx
@@ -28,7 +28,7 @@ const INITIAL_WIZARD_STATE: WizardState = {
     annualSpending: 60000,
     totalAnnualContribution: 25000,
     contributionAllocation: { taxDeferred: 50, taxable: 30, taxExempt: 20 },
-    futureIncome: { socialSecurity: 35000, socialSecurityStartAge: 67, pension: 0 }
+    futureIncome: { socialSecurity: 35000, socialSecurityStartAge: 67, pension: 0, spouseSocialSecurity: 0, spouseSocialSecurityStartAge: 67 }
 };
 
 const WizardModal: React.FC<WizardModalProps> = ({ isOpen, onClose, onComplete, currentProfile }) => {
diff --git a/src/components/features/wizard/types.ts b/src/components/features/wizard/types.ts
index 2211066..75248f8 100644
--- a/src/components/features/wizard/types.ts
+++ b/src/components/features/wizard/types.ts
@@ -22,5 +22,7 @@ export interface WizardState {
         socialSecurity: number;
         socialSecurityStartAge: number;
         pension: number;
+        spouseSocialSecurity: number;
+        spouseSocialSecurityStartAge: number;
     };
 }
diff --git a/src/components/features/wizard/wizardMapper.ts b/src/components/features/wizard/wizardMapper.ts
index 5ec07ef..6de6fcf 100644
--- a/src/components/features/wizard/wizardMapper.ts
+++ b/src/components/features/wizard/wizardMapper.ts
@@ -22,6 +22,9 @@ export const mapWizardStateToProfile = (wizardState: WizardState, currentProfile
         age: retirementAge,
         baseAge: currentAge,
         filingStatus: filingStatus,
+        spouseAge: currentProfile.spouseAge || 0,
+        spouseSocialSecurity: futureIncome.spouseSocialSecurity || 0,
+        spouseSocialSecurityStartAge: futureIncome.spouseSocialSecurityStartAge || 67,
         spendingNeed: annualSpending,
         isSpendingReal: true, // Defaulting to today's dollars as per requirements
         assets: {
diff --git a/src/services/calculationEngine.ts b/src/services/calculationEngine.ts
index c271ac6..adb27fa 100644
--- a/src/services/calculationEngine.ts
+++ b/src/services/calculationEngine.ts
@@ -69,6 +69,24 @@ export const calculateSEPPPayment = (balance: number, age: number): number => {
   return balance * (numerator / denominator);
 };
 
+/**
+ * Calculates the additional standard deduction for age 65+.
+ * For MFJ, checks each spouse's age independently.
+ */
+const calculateAgeDeduction = (
+  primaryAge: number,
+  filingStatus: FilingStatus,
+  spouseAge: number = 0
+): number => {
+  if (filingStatus === FilingStatus.MarriedJoint) {
+    let deduction = 0;
+    if (primaryAge >= 65) deduction += AGE_DEDUCTION[filingStatus];
+    if (spouseAge >= 65) deduction += AGE_DEDUCTION[filingStatus];
+    return deduction;
+  }
+  return primaryAge >= 65 ? AGE_DEDUCTION[filingStatus] : 0;
+};
+
 export const getWithdrawalOrder = (
   age: number,
   assets: Assets,
@@ -229,6 +247,14 @@ export const calculateStrategy = (profile: UserProfile): StrategyResult => {
   const isSSActive = age >= (income.socialSecurityStartAge || 62);
   const annualSS = isSSActive ? income.socialSecurity : 0;
 
+  // Partner Social Security (MFJ only) — spouseAge is partner's age at retirement start
+  const spouseAgeAtRetirement = filingStatus === FilingStatus.MarriedJoint
+    ? (profile.spouseAge || 0) : 0;
+  const spouseSSStartAge = profile.spouseSocialSecurityStartAge || 67;
+  const isSpouseSSActive = filingStatus === FilingStatus.MarriedJoint && spouseAgeAtRetirement >= spouseSSStartAge;
+  const annualSpouseSS = isSpouseSSActive ? (profile.spouseSocialSecurity || 0) : 0;
+  const totalAnnualSS = annualSS + annualSpouseSS;
+
   // Calculate annual dividends based on yield (Static for Strategy, Logic handles depletion in Longevity)
   // For the 'Year 1' strategy snapshot, we use the full balance.
   const brokerageDividends = assets.brokerage * income.brokerageDividendYield;
@@ -239,7 +265,7 @@ export const calculateStrategy = (profile: UserProfile): StrategyResult => {
   }
 
   const standardDeduction = STANDARD_DEDUCTION[filingStatus] +
-    (age >= 65 ? AGE_DEDUCTION[filingStatus] * (filingStatus === FilingStatus.MarriedJoint ? 2 : 1) : 0);
+    calculateAgeDeduction(age, filingStatus, spouseAgeAtRetirement);
 
   const qualifiedDividends = brokerageDividends * income.qualifiedDividendRatio;
   const ordinaryDividends = brokerageDividends * (1 - income.qualifiedDividendRatio);
@@ -259,7 +285,7 @@ export const calculateStrategy = (profile: UserProfile): StrategyResult => {
     let currentRothBasis = assets.rothBasis || 0;
 
     const withdrawalPlan: WithdrawalSource[] = [];
-    let grossCash = annualSS + income.pension + brokerageDividends;
+    let grossCash = totalAnnualSS + income.pension + brokerageDividends;
     let ordIncomeForTax = income.pension + ordinaryDividends;
     let capGainsForTax = qualifiedDividends;
     let currentPenalty = 0;
@@ -343,7 +369,7 @@ export const calculateStrategy = (profile: UserProfile): StrategyResult => {
     // Check if we failed to fill gap even with penalties, OR if we triggered penalties
     liquidityGapWarning = gap > 1 || currentPenalty > 0;
 
-    const finalTaxableSS = calculateTaxableSocialSecurity(annualSS, ordIncomeForTax, filingStatus);
+    const finalTaxableSS = calculateTaxableSocialSecurity(totalAnnualSS, ordIncomeForTax, filingStatus);
     const iterationTax = calculateFederalTax(ordIncomeForTax + finalTaxableSS, capGainsForTax, filingStatus, standardDeduction);
 
     lastResult = {
@@ -356,8 +382,8 @@ export const calculateStrategy = (profile: UserProfile): StrategyResult => {
       effectiveTaxRate: iterationTax / (grossCash || 1),
       rmdAmount,
       taxableSocialSecurity: finalTaxableSS,
-      currentYearSocialSecurity: annualSS,
-      provisionalIncome: ordIncomeForTax + (0.5 * annualSS),
+      currentYearSocialSecurity: totalAnnualSS,
+      provisionalIncome: ordIncomeForTax + (0.5 * totalAnnualSS),
       standardDeduction,
       notes: currentPenalty > 0 ? [`Includes $${currentPenalty.toFixed(0)} early withdrawal penalty.`] : [],
       nominalSpendingNeeded
@@ -427,12 +453,24 @@ export const calculateLongevity = (profile: UserProfile, strategy: StrategyResul
 
     // 1. Calculate Inflows (SS + Pension + Dynamic Dividends)
     const ssStartAge = profile.income.socialSecurityStartAge || 62;
-    let currentSS = 0;
+    let currentPrimarySS = 0;
     if (age >= ssStartAge) {
       const yearsSinceStart = age - ssStartAge;
-      currentSS = profile.income.socialSecurity * Math.pow(1 + profile.assumptions.inflationRateInRetirement, yearsSinceStart);
+      currentPrimarySS = profile.income.socialSecurity * Math.pow(1 + profile.assumptions.inflationRateInRetirement, yearsSinceStart);
     }
 
+    // Partner SS (MFJ only) — spouseAge is partner's age at retirement start
+    const spouseRetirementAge = profile.spouseAge || 0;
+    const spouseAgeThisYear = spouseRetirementAge + i;
+    const spouseSSStartAge = profile.spouseSocialSecurityStartAge || 67;
+    let currentSpouseSS = 0;
+    if (profile.filingStatus === FilingStatus.MarriedJoint && spouseAgeThisYear >= spouseSSStartAge) {
+      const yearsSinceSpouseStart = spouseAgeThisYear - spouseSSStartAge;
+      currentSpouseSS = (profile.spouseSocialSecurity || 0) * Math.pow(1 + profile.assumptions.inflationRateInRetirement, yearsSinceSpouseStart);
+    }
+
+    const currentSS = currentPrimarySS + currentSpouseSS;
+
     // Dynamic Dividend calculation based on START of year brokerage balance
     const currentDividends = currentBrokerage * divYield;
 
@@ -561,7 +599,7 @@ export const calculateLongevity = (profile: UserProfile, strategy: StrategyResul
 
     const taxableSS = calculateTaxableSocialSecurity(currentSS, totalOrdinaryForTax, profile.filingStatus);
     const stdDeduction = STANDARD_DEDUCTION[profile.filingStatus] +
-      (age >= 65 ? AGE_DEDUCTION[profile.filingStatus] * (profile.filingStatus === FilingStatus.MarriedJoint ? 2 : 1) : 0);
+      calculateAgeDeduction(age, profile.filingStatus, spouseAgeThisYear);
 
     const estimatedTax = calculateFederalTax(totalOrdinaryForTax + taxableSS, totalCapGainsForTax, profile.filingStatus, stdDeduction);
     const totalCashFlow = fromBrokerage + fromTrad + fromRoth + fromHSA + totalFixedIncome;
@@ -705,13 +743,22 @@ const getIRMAATierInfo = (
 const calculateSeniorDeduction = (
   age: number,
   magi: number,
-  filingStatus: FilingStatus
+  filingStatus: FilingStatus,
+  spouseAge: number = 0
 ): { deduction: number; headroomToPhaseout: number; inPhaseout: boolean } => {
-  if (age < 65) {
+  // Calculate per-person eligibility for MFJ ($6k per spouse if 65+)
+  let baseDeduction = 0;
+  if (filingStatus === FilingStatus.MarriedJoint) {
+    if (age >= 65) baseDeduction += 6000;
+    if (spouseAge >= 65) baseDeduction += 6000;
+  } else {
+    if (age >= 65) baseDeduction = SENIOR_DEDUCTION[filingStatus];
+  }
+
+  if (baseDeduction === 0) {
     return { deduction: 0, headroomToPhaseout: Infinity, inPhaseout: false };
   }
 
-  const baseDeduction = SENIOR_DEDUCTION[filingStatus];
   const phaseout = SENIOR_DEDUCTION_PHASEOUT[filingStatus];
 
   if (magi <= phaseout.start) {
@@ -753,7 +800,14 @@ export const calculateRothConversionOptimization = (
 
   // Use the passed active SS amount or default to profile (logic should prefer the passed active amount)
   // If activeSocialSecurityAmount is defined, use it. Otherwise rely on profile check.
-  const ssAmount = activeSocialSecurityAmount !== undefined ? activeSocialSecurityAmount : income.socialSecurity;
+  const primarySSAmount = activeSocialSecurityAmount !== undefined ? activeSocialSecurityAmount : income.socialSecurity;
+
+  // Include partner SS for MFJ — spouseAge is partner's age at retirement start
+  const spouseAgeAtRetirement = filingStatus === FilingStatus.MarriedJoint
+    ? (profile.spouseAge || 0) : 0;
+  const spouseSSStartAge = profile.spouseSocialSecurityStartAge || 67;
+  const spouseSSActive = filingStatus === FilingStatus.MarriedJoint && spouseAgeAtRetirement >= spouseSSStartAge;
+  const ssAmount = primarySSAmount + (spouseSSActive ? (profile.spouseSocialSecurity || 0) : 0);
 
   // ========================================
   // SUSTAINABILITY OVERRIDE (Fiduciary Safety Check)
@@ -801,7 +855,7 @@ export const calculateRothConversionOptimization = (
 
   // Standard deduction for base calculations
   const standardDeduction = STANDARD_DEDUCTION[filingStatus] +
-    (age >= 65 ? AGE_DEDUCTION[filingStatus] * (filingStatus === FilingStatus.MarriedJoint ? 2 : 1) : 0);
+    calculateAgeDeduction(age, filingStatus, spouseAgeAtRetirement);
 
   // Current taxable income
   const currentTaxableIncome = Math.max(0, currentOrdinaryIncome + taxableSS - standardDeduction);
@@ -841,7 +895,7 @@ export const calculateRothConversionOptimization = (
   // ========================================
   // CONSTRAINT 3: Senior Deduction Phase-Out
   // ========================================
-  const seniorInfo = calculateSeniorDeduction(age, currentMAGI, filingStatus);
+  const seniorInfo = calculateSeniorDeduction(age, currentMAGI, filingStatus, spouseAgeAtRetirement);
   if (age >= 65 && seniorInfo.headroomToPhaseout < Infinity) {
     constraints.push({
       type: 'senior_phaseout',
diff --git a/src/types/core.ts b/src/types/core.ts
index b88e8a6..07f06d2 100644
--- a/src/types/core.ts
+++ b/src/types/core.ts
@@ -43,6 +43,9 @@ export interface UserProfile {
   age: number; // Retirement Start Age (Start of Withdrawals)
   baseAge: number; // Current Age (Start of Plan/Inflation Anchor)
   filingStatus: FilingStatus;
+  spouseAge: number; // Partner's age at retirement start (for MFJ age-65+ deduction)
+  spouseSocialSecurity: number; // Spouse's annual SS benefit
+  spouseSocialSecurityStartAge: number; // Spouse's SS start age
   spendingNeed: number;
   isSpendingReal: boolean; // Is the spending need in today's dollars?
   assets: Assets;