wallet: Have GetBalance report used amount directly without two calls

diff --git a/src/interfaces/wallet.h b/src/interfaces/wallet.h
index 2ccd514d..118f9a2e 100644
--- a/src/interfaces/wallet.h
+++ b/src/interfaces/wallet.h
@@ -369,11 +369,13 @@ struct WalletBalances
     CAmount balance = 0;
     CAmount unconfirmed_balance = 0;
     CAmount immature_balance = 0;
+    CAmount used_balance = 0;
 
     bool balanceChanged(const WalletBalances& prev) const
     {
         return balance != prev.balance || unconfirmed_balance != prev.unconfirmed_balance ||
-               immature_balance != prev.immature_balance;
+               immature_balance != prev.immature_balance ||
+               used_balance != prev.used_balance;
     }
 };
 
diff --git a/src/wallet/interfaces.cpp b/src/wallet/interfaces.cpp
index 4dc87334..7fa0d8a1 100644
--- a/src/wallet/interfaces.cpp
+++ b/src/wallet/interfaces.cpp
@@ -388,6 +388,7 @@ public:
         result.balance = bal.m_mine_trusted;
         result.unconfirmed_balance = bal.m_mine_untrusted_pending;
         result.immature_balance = bal.m_mine_immature;
+        result.used_balance = bal.m_mine_used;
         return result;
     }
     bool tryGetBalances(WalletBalances& balances, uint256& block_hash) override
diff --git a/src/wallet/receive.cpp b/src/wallet/receive.cpp
index 13a25b36..8832ddb6 100644
--- a/src/wallet/receive.cpp
+++ b/src/wallet/receive.cpp
@@ -255,17 +255,25 @@ Balance GetBalance(const CWallet& wallet, const int min_depth, bool avoid_reuse)
             const bool is_trusted{CachedTxIsTrusted(wallet, wtx, trusted_parents)};
             const int tx_depth{wallet.GetTxDepthInMainChain(wtx)};
 
-            if (!wallet.IsSpent(outpoint) && (allow_used_addresses || !wallet.IsSpentKey(txo.GetTxOut().scriptPubKey))) {
-                // Get the amounts for mine
-                CAmount credit_mine = txo.GetTxOut().nValue;
+            if (!wallet.IsSpent(outpoint)) {
+                CAmount* bucket = nullptr;
 
                 // Set the amounts in the return object
                 if (wallet.IsTxImmatureCoinBase(wtx) && wtx.isConfirmed()) {
-                    ret.m_mine_immature += credit_mine;
+                    bucket = &ret.m_mine_immature;
                 } else if (is_trusted && tx_depth >= min_depth) {
-                    ret.m_mine_trusted += credit_mine;
+                    bucket = &ret.m_mine_trusted;
                 } else if (!is_trusted && wtx.InMempool()) {
-                    ret.m_mine_untrusted_pending += credit_mine;
+                    bucket = &ret.m_mine_untrusted_pending;
+                }
+                if (bucket) {
+                    // Get the amounts for mine
+                    CAmount credit_mine = txo.GetTxOut().nValue;
+
+                    if (!allow_used_addresses && wallet.IsSpentKey(txo.GetTxOut().scriptPubKey)) {
+                        bucket = &ret.m_mine_used;
+                    }
+                    *bucket += credit_mine;
                 }
             }
         }
diff --git a/src/wallet/receive.h b/src/wallet/receive.h
index f6c55a45..5bc0545b 100644
--- a/src/wallet/receive.h
+++ b/src/wallet/receive.h
@@ -47,6 +47,7 @@ struct Balance {
     CAmount m_mine_trusted{0};           //!< Trusted, at depth=GetBalance.min_depth or more
     CAmount m_mine_untrusted_pending{0}; //!< Untrusted, but in mempool (pending)
     CAmount m_mine_immature{0};          //!< Immature coinbases in the main chain
+    CAmount m_mine_used{0};              //!< Trusted/untrusted/immature funds in utxos that have already been spent from (only populated if AVOID REUSE wallet flag is set)
 };
 Balance GetBalance(const CWallet& wallet, int min_depth = 0, bool avoid_reuse = true);
 
diff --git a/src/wallet/rpc/coins.cpp b/src/wallet/rpc/coins.cpp
index 4aef0dda..c76d5e3c 100644
--- a/src/wallet/rpc/coins.cpp
+++ b/src/wallet/rpc/coins.cpp
@@ -433,7 +433,8 @@ RPCHelpMan getbalances()
 
     LOCK(wallet.cs_wallet);
 
-    const auto bal = GetBalance(wallet);
+    const auto bal = GetBalance(wallet, /*min_depth=*/0, /*avoid_reuse=*/true);
+
     UniValue balances{UniValue::VOBJ};
     {
         UniValue balances_mine{UniValue::VOBJ};
@@ -441,10 +442,7 @@ RPCHelpMan getbalances()
         balances_mine.pushKV("untrusted_pending", ValueFromAmount(bal.m_mine_untrusted_pending));
         balances_mine.pushKV("immature", ValueFromAmount(bal.m_mine_immature));
         if (wallet.IsWalletFlagSet(WALLET_FLAG_AVOID_REUSE)) {
-            // If the AVOID_REUSE flag is set, bal has been set to just the un-reused address balance. Get
-            // the total balance, and then subtract bal to get the reused address balance.
-            const auto full_bal = GetBalance(wallet, 0, false);
-            balances_mine.pushKV("used", ValueFromAmount(full_bal.m_mine_trusted + full_bal.m_mine_untrusted_pending - bal.m_mine_trusted - bal.m_mine_untrusted_pending));
+            balances_mine.pushKV("used", ValueFromAmount(bal.m_mine_used));
         }
         balances.pushKV("mine", std::move(balances_mine));
     }