diff --git a/models.py b/models.py
index abd508f..2d6b861 100644
--- a/models.py
+++ b/models.py
@@ -186,10 +186,12 @@ class SettleReceivable(BaseModel):
     """Manually settle a receivable (user pays castle in person)"""
 
     user_id: str
-    amount: int  # Amount in satoshis
+    amount: Decimal  # Amount in the specified currency (or satoshis if currency is None)
     payment_method: str  # "cash", "bank_transfer", "lightning", "other"
     description: str  # Description of the payment
     reference: Optional[str] = None  # Optional reference (receipt number, transaction ID, etc.)
+    currency: Optional[str] = None  # If None, amount is in satoshis. Otherwise, fiat currency code (EUR, USD, etc.)
+    amount_sats: Optional[int] = None  # Equivalent amount in sats (for reference/conversion tracking)
 
 
 class AssertionStatus(str, Enum):
diff --git a/static/js/index.js b/static/js/index.js
index 82272a0..2d76093 100644
--- a/static/js/index.js
+++ b/static/js/index.js
@@ -96,7 +96,9 @@ window.app = Vue.createApp({
         invoice: null,
         paymentHash: null,
         checkWalletKey: null,
-        pollIntervalId: null
+        pollIntervalId: null,
+        exchangeRate: 3571.43, // sats per EUR (TODO: fetch from API)
+        originalCurrency: 'BTC' // Track original receivable currency
       }
     }
   },
@@ -114,6 +116,25 @@ window.app = Vue.createApp({
         clearInterval(this.settleReceivableDialog.pollIntervalId)
         this.settleReceivableDialog.pollIntervalId = null
       }
+    },
+    'settleReceivableDialog.payment_method': function(newVal, oldVal) {
+      // Convert amount when payment method changes between cash and lightning
+      if (!oldVal) return
+
+      const isOldCash = ['cash', 'bank_transfer', 'check'].includes(oldVal)
+      const isNewCash = ['cash', 'bank_transfer', 'check'].includes(newVal)
+
+      // Only convert if switching between cash and lightning
+      if (isOldCash === isNewCash) return
+
+      // Convert from fiat to sats (when switching from cash to lightning)
+      if (isOldCash && !isNewCash) {
+        this.settleReceivableDialog.amount = this.settleReceivableDialog.maxAmount
+      }
+      // Convert from sats to fiat (when switching from lightning to cash)
+      else if (!isOldCash && isNewCash) {
+        this.settleReceivableDialog.amount = this.settleReceivableDialog.maxAmountFiat || 0
+      }
     }
   },
   computed: {
@@ -135,6 +156,30 @@ window.app = Vue.createApp({
       }
       return 'Amount (sats) *'
     },
+    settlementAmountLabel() {
+      const isCashPayment = ['cash', 'bank_transfer', 'check'].includes(
+        this.settleReceivableDialog.payment_method
+      )
+      if (isCashPayment && this.settleReceivableDialog.fiatCurrency) {
+        return `Settlement Amount (${this.settleReceivableDialog.fiatCurrency}) *`
+      }
+      return 'Settlement Amount (sats) *'
+    },
+    settlementMaxAmount() {
+      const isCashPayment = ['cash', 'bank_transfer', 'check'].includes(
+        this.settleReceivableDialog.payment_method
+      )
+      if (isCashPayment && this.settleReceivableDialog.maxAmountFiat) {
+        return this.settleReceivableDialog.maxAmountFiat
+      }
+      return this.settleReceivableDialog.maxAmount
+    },
+    settlementAmountStep() {
+      const isCashPayment = ['cash', 'bank_transfer', 'check'].includes(
+        this.settleReceivableDialog.payment_method
+      )
+      return isCashPayment ? '0.01' : '1'
+    },
     currencyOptions() {
       const options = [{label: 'Satoshis (default)', value: null}]
       this.currencies.forEach(curr => {
@@ -883,20 +928,29 @@ window.app = Vue.createApp({
         clearInterval(this.settleReceivableDialog.pollIntervalId)
       }
 
+      // Extract fiat balances (e.g., EUR)
+      const fiatBalances = userBalance.fiat_balances || {}
+      const fiatCurrency = Object.keys(fiatBalances)[0] || null // Get first fiat currency (e.g., 'EUR')
+      const fiatAmount = fiatCurrency ? Math.abs(fiatBalances[fiatCurrency]) : 0
+
       this.settleReceivableDialog = {
         show: true,
         user_id: userBalance.user_id,
         username: userBalance.username,
-        maxAmount: Math.abs(userBalance.balance), // Convert negative to positive
-        amount: Math.abs(userBalance.balance), // Default to full amount
-        payment_method: 'lightning',
+        maxAmount: Math.abs(userBalance.balance), // Sats amount
+        maxAmountFiat: fiatAmount, // EUR or other fiat amount
+        fiatCurrency: fiatCurrency, // 'EUR', 'USD', etc.
+        amount: fiatCurrency ? fiatAmount : Math.abs(userBalance.balance), // Default to fiat if available, otherwise sats
+        payment_method: fiatCurrency ? 'cash' : 'lightning', // Default to cash if fiat balance exists
         description: `Payment from ${userBalance.username}`,
         reference: '',
         loading: false,
         invoice: null,
         paymentHash: null,
         checkWalletKey: null,
-        pollIntervalId: null
+        pollIntervalId: null,
+        exchangeRate: fiatAmount > 0 ? Math.abs(userBalance.balance) / fiatAmount : 3571.43, // Calculate rate from actual amounts
+        originalCurrency: fiatCurrency || 'BTC'
       }
     },
     async generateSettlementInvoice() {
@@ -1018,17 +1072,30 @@ window.app = Vue.createApp({
     async submitSettleReceivable() {
       this.settleReceivableDialog.loading = true
       try {
+        // Determine if this is a fiat payment
+        const isCashPayment = ['cash', 'bank_transfer', 'check'].includes(
+          this.settleReceivableDialog.payment_method
+        )
+
+        const payload = {
+          user_id: this.settleReceivableDialog.user_id,
+          amount: this.settleReceivableDialog.amount,
+          payment_method: this.settleReceivableDialog.payment_method,
+          description: this.settleReceivableDialog.description,
+          reference: this.settleReceivableDialog.reference || null,
+        }
+
+        // Add currency info for fiat payments
+        if (isCashPayment && this.settleReceivableDialog.fiatCurrency) {
+          payload.currency = this.settleReceivableDialog.fiatCurrency
+          payload.amount_sats = this.settleReceivableDialog.maxAmount
+        }
+
         const response = await LNbits.api.request(
           'POST',
           '/castle/api/v1/receivables/settle',
           this.g.user.wallets[0].adminkey,
-          {
-            user_id: this.settleReceivableDialog.user_id,
-            amount: this.settleReceivableDialog.amount,
-            payment_method: this.settleReceivableDialog.payment_method,
-            description: this.settleReceivableDialog.description,
-            reference: this.settleReceivableDialog.reference || null
-          }
+          payload
         )
 
         this.$q.notify({
diff --git a/templates/castle/index.html b/templates/castle/index.html
index c75bcec..a198d25 100644
--- a/templates/castle/index.html
+++ b/templates/castle/index.html
@@ -1138,7 +1138,12 @@
 
       <div class="q-mb-md">
         <div class="text-subtitle2">Amount Owed</div>
-        <div class="text-negative text-h6">{% raw %}{{ formatSats(settleReceivableDialog.maxAmount) }}{% endraw %} sats</div>
+        <div class="text-negative text-h6">
+          {% raw %}{{ formatSats(settleReceivableDialog.maxAmount) }}{% endraw %} sats
+        </div>
+        <div v-if="settleReceivableDialog.fiatCurrency && settleReceivableDialog.maxAmountFiat" class="text-caption">
+          {% raw %}{{ formatFiat(settleReceivableDialog.maxAmountFiat, settleReceivableDialog.fiatCurrency) }}{% endraw %}
+        </div>
       </div>
 
       <q-input
@@ -1146,13 +1151,14 @@
         dense
         v-model.number="settleReceivableDialog.amount"
         type="number"
-        label="Settlement Amount (sats) *"
+        :label="settlementAmountLabel"
         hint="Amount user is paying (max: owed amount)"
-        :max="settleReceivableDialog.maxAmount"
+        :max="settlementMaxAmount"
+        :step="settlementAmountStep"
         :rules="[
           val => val !== null && val !== undefined && val !== '' || 'Amount is required',
           val => val > 0 || 'Amount must be positive',
-          val => val <= settleReceivableDialog.maxAmount || 'Cannot exceed owed amount'
+          val => val <= settlementMaxAmount || 'Cannot exceed owed amount'
         ]"
       ></q-input>
 
diff --git a/views_api.py b/views_api.py
index e256320..f6a41dc 100644
--- a/views_api.py
+++ b/views_api.py
@@ -826,6 +826,26 @@ async def api_settle_receivable(
     # DR Cash/Bank (asset increased), CR Accounts Receivable (asset decreased)
     # This records that user paid their debt
 
+    # Convert amount to sats (minor units)
+    # For fiat currencies, store as cents/minor units
+    # For satoshis, just convert to int
+    from decimal import Decimal
+
+    if data.currency:
+        # Fiat currency payment (e.g., EUR, USD)
+        amount_minor_units = int(data.amount * 100)  # Convert to cents
+        line_metadata = {
+            "fiat_currency": data.currency,
+            "fiat_amount": str(data.amount),
+        }
+        if data.amount_sats:
+            line_metadata["sats_equivalent"] = data.amount_sats
+            line_metadata["exchange_rate"] = data.amount_sats / float(data.amount)
+    else:
+        # Satoshi payment
+        amount_minor_units = int(data.amount)
+        line_metadata = {}
+
     # Add meta information for audit trail
     entry_meta = {
         "source": "manual_settlement",
@@ -833,6 +853,8 @@ async def api_settle_receivable(
         "settled_by": wallet.wallet.user,
         "payer_user_id": data.user_id,
     }
+    if data.currency:
+        entry_meta["currency"] = data.currency
 
     entry_data = CreateJournalEntry(
         description=data.description,
@@ -842,15 +864,17 @@ async def api_settle_receivable(
         lines=[
             CreateEntryLine(
                 account_id=payment_account.id,
-                debit=data.amount,
+                debit=amount_minor_units,
                 credit=0,
                 description=f"Payment received via {data.payment_method}",
+                metadata=line_metadata,
             ),
             CreateEntryLine(
                 account_id=user_receivable.id,
                 debit=0,
-                credit=data.amount,
+                credit=amount_minor_units,
                 description="Receivable settled",
+                metadata=line_metadata,
             ),
         ],
     )
@@ -863,7 +887,8 @@ async def api_settle_receivable(
     return {
         "journal_entry_id": entry.id,
         "user_id": data.user_id,
-        "amount_settled": data.amount,
+        "amount_settled": float(data.amount),
+        "currency": data.currency,
         "payment_method": data.payment_method,
         "new_balance": balance.balance,
         "message": f"Receivable settled successfully via {data.payment_method}",