diff --git a/src/ripple/app/ledger/impl/LedgerToJson.cpp b/src/ripple/app/ledger/impl/LedgerToJson.cpp
index 81e84303933..26f1ca2aefd 100644
--- a/src/ripple/app/ledger/impl/LedgerToJson.cpp
+++ b/src/ripple/app/ledger/impl/LedgerToJson.cpp
@@ -17,6 +17,7 @@
 */
 //==============================================================================
 
+#include <ripple/app/ledger/LedgerMaster.h>
 #include <ripple/app/ledger/LedgerToJson.h>
 #include <ripple/app/main/Application.h>
 #include <ripple/app/misc/DeliverMax.h>
@@ -26,6 +27,7 @@
 #include <ripple/protocol/jss.h>
 #include <ripple/rpc/Context.h>
 #include <ripple/rpc/DeliveredAmount.h>
+#include <ripple/rpc/impl/RPCHelpers.h>
 
 namespace ripple {
 
@@ -137,7 +139,6 @@ fillJsonTx(
                 txn->getJson(
                     JsonOptions::none, false, {std::optional(std::ref(hash))}));
             txJson[jss::hash] = hash;
-            // TODO set `txJson[jss::close_time_iso]`
             RPC::insertDeliverMax(
                 txJson[jss::tx_json], txnType, fill.context->apiVersion);
 
@@ -153,6 +154,17 @@ fillJsonTx(
                         txn,
                         {txn->getTransactionID(), fill.ledger.seq(), *stMeta});
             }
+
+            const bool validated = RPC::isValidated(
+                fill.context->ledgerMaster, fill.ledger, fill.context->app);
+            txJson[jss::validated] = validated;
+            if (validated)
+            {
+                if (auto close_time =
+                        fill.context->ledgerMaster.getCloseTimeBySeq(
+                            fill.ledger.seq()))
+                    txJson[jss::close_time_iso] = to_string_iso(*close_time);
+            }
         }
         else
         {
diff --git a/src/ripple/app/misc/NetworkOPs.cpp b/src/ripple/app/misc/NetworkOPs.cpp
index 27dba963422..7c79c1b68e1 100644
--- a/src/ripple/app/misc/NetworkOPs.cpp
+++ b/src/ripple/app/misc/NetworkOPs.cpp
@@ -3124,6 +3124,8 @@ NetworkOPsImp::transJson(
         jvObj[jss::transaction][jss::date] =
             ledger->info().closeTime.time_since_epoch().count();
         jvObj[jss::validated] = true;
+        if (auto close_time = m_ledgerMaster.getCloseTimeBySeq(ledger->seq()))
+            jvObj[jss::close_time_iso] = to_string_iso(*close_time);
 
         // WRITEME: Put the account next seq here
     }
diff --git a/src/ripple/basics/chrono.h b/src/ripple/basics/chrono.h
index f50d765d58f..21353e0873a 100644
--- a/src/ripple/basics/chrono.h
+++ b/src/ripple/basics/chrono.h
@@ -25,6 +25,7 @@
 #include <ripple/beast/clock/abstract_clock.h>
 #include <ripple/beast/clock/basic_seconds_clock.h>
 #include <ripple/beast/clock/manual_clock.h>
+
 #include <chrono>
 #include <cstdint>
 #include <string>
@@ -43,8 +44,19 @@ using weeks = std::chrono::
 /** Clock for measuring the network time.
 
     The epoch is January 1, 2000
-    epoch_offset = days(10957);  // 2000-01-01
+
+    epoch_offset
+    = date(2000-01-01) - date(1970-0-01)
+    = days(10957)
+    = seconds(946684800)
 */
+
+constexpr static std::chrono::seconds epoch_offset =
+    date::sys_days{date::year{2000} / 1 / 1} -
+    date::sys_days{date::year{1970} / 1 / 1};
+
+static_assert(epoch_offset.count() == 946684800);
+
 class NetClock
 {
 public:
@@ -71,7 +83,24 @@ to_string(NetClock::time_point tp)
     // 2000-01-01 00:00:00 UTC is 946684800s from 1970-01-01 00:00:00 UTC
     using namespace std::chrono;
     return to_string(
-        system_clock::time_point{tp.time_since_epoch() + 946684800s});
+        system_clock::time_point{tp.time_since_epoch() + epoch_offset});
+}
+
+template <class Duration>
+std::string
+to_string_iso(date::sys_time<Duration> tp)
+{
+    using namespace std::chrono;
+    return date::format("%FT%H:%M:%OSZ", tp);
+}
+
+inline std::string
+to_string_iso(NetClock::time_point tp)
+{
+    // 2000-01-01 00:00:00 UTC is 946684800s from 1970-01-01 00:00:00 UTC
+    using namespace std::chrono;
+    return to_string_iso(
+        system_clock::time_point{tp.time_since_epoch() + epoch_offset});
 }
 
 /** A clock for measuring elapsed time.
diff --git a/src/ripple/core/TimeKeeper.h b/src/ripple/core/TimeKeeper.h
index 55970ec8227..e239a2f7565 100644
--- a/src/ripple/core/TimeKeeper.h
+++ b/src/ripple/core/TimeKeeper.h
@@ -22,6 +22,7 @@
 
 #include <ripple/basics/chrono.h>
 #include <ripple/beast/clock/abstract_clock.h>
+
 #include <atomic>
 
 namespace ripple {
@@ -37,7 +38,7 @@ class TimeKeeper : public beast::abstract_clock<NetClock>
     adjust(std::chrono::system_clock::time_point when)
     {
         return time_point(std::chrono::duration_cast<duration>(
-            when.time_since_epoch() - days(10957)));
+            when.time_since_epoch() - epoch_offset));
     }
 
 public:
diff --git a/src/ripple/protocol/jss.h b/src/ripple/protocol/jss.h
index 281a410127d..8a701defad8 100644
--- a/src/ripple/protocol/jss.h
+++ b/src/ripple/protocol/jss.h
@@ -230,6 +230,8 @@ JSS(close);                       // out: BookChanges
 JSS(close_flags);                 // out: LedgerToJson
 JSS(close_time);                  // in: Application, out: NetworkOPs,
                                   //      RCLCxPeerPos, LedgerToJson
+JSS(close_time_iso);              // out: Tx, NetworkOPs, TransactionEntry
+                                  //      AccountTx, LedgerToJson
 JSS(close_time_estimated);        // in: Application, out: LedgerToJson
 JSS(close_time_human);            // out: LedgerToJson
 JSS(close_time_offset);           // out: NetworkOPs
diff --git a/src/ripple/rpc/handlers/AMMInfo.cpp b/src/ripple/rpc/handlers/AMMInfo.cpp
index 11e124afb44..47d3e117e8e 100644
--- a/src/ripple/rpc/handlers/AMMInfo.cpp
+++ b/src/ripple/rpc/handlers/AMMInfo.cpp
@@ -66,7 +66,7 @@ to_iso8601(NetClock::time_point tp)
     return date::format(
         "%Y-%Om-%dT%H:%M:%OS%z",
         date::sys_time<system_clock::duration>(
-            system_clock::time_point{tp.time_since_epoch() + 946684800s}));
+            system_clock::time_point{tp.time_since_epoch() + epoch_offset}));
 }
 
 Json::Value
diff --git a/src/ripple/rpc/handlers/AccountTx.cpp b/src/ripple/rpc/handlers/AccountTx.cpp
index 2a4ae3648e3..8f130daadf5 100644
--- a/src/ripple/rpc/handlers/AccountTx.cpp
+++ b/src/ripple/rpc/handlers/AccountTx.cpp
@@ -334,7 +334,6 @@ populateJsonResponse(
                         jvObj[json_tx] = txn->getJson(
                             JsonOptions::include_date, false, {std::ref(hash)});
                         jvObj[jss::hash] = hash;
-                        // TODO set `jvObj[jss::close_time_iso]`
                     }
                     else
                         jvObj[json_tx] =
@@ -351,6 +350,11 @@ populateJsonResponse(
                         insertDeliveredAmount(
                             jvObj[jss::meta], context, txn, *txnMeta);
                         insertNFTSyntheticInJson(jvObj, sttx, *txnMeta);
+                        if (auto closeTime =
+                                context.ledgerMaster.getCloseTimeBySeq(
+                                    txnMeta->getIndex()))
+                            jvObj[jss::close_time_iso] =
+                                to_string_iso(*closeTime);
                     }
                 }
             }
diff --git a/src/ripple/rpc/handlers/TransactionEntry.cpp b/src/ripple/rpc/handlers/TransactionEntry.cpp
index b7956168848..db826f57d37 100644
--- a/src/ripple/rpc/handlers/TransactionEntry.cpp
+++ b/src/ripple/rpc/handlers/TransactionEntry.cpp
@@ -17,6 +17,7 @@
 */
 //==============================================================================
 
+#include <ripple/app/ledger/LedgerMaster.h>
 #include <ripple/app/main/Application.h>
 #include <ripple/app/misc/DeliverMax.h>
 #include <ripple/ledger/ReadView.h>
@@ -77,7 +78,18 @@ doTransactionEntry(RPC::JsonContext& context)
                 jvResult[jss::tx_json] =
                     sttx->getJson(JsonOptions::none, false, {std::ref(hash)});
                 jvResult[jss::hash] = hash;
-                // TODO set `jvResult[jss::close_time_iso]`
+
+                bool const validated = RPC::isValidated(
+                    context.ledgerMaster, *lpLedger, context.app);
+
+                jvResult[jss::validated] = validated;
+                if (validated)
+                {
+                    if (auto closeTime = context.ledgerMaster.getCloseTimeBySeq(
+                            lpLedger->seq()))
+                        jvResult[jss::close_time_iso] =
+                            to_string_iso(*closeTime);
+                }
             }
             else
                 jvResult[jss::tx_json] = sttx->getJson(JsonOptions::none);
diff --git a/src/ripple/rpc/handlers/Tx.cpp b/src/ripple/rpc/handlers/Tx.cpp
index 3769f38a05d..16fa7baa8ba 100644
--- a/src/ripple/rpc/handlers/Tx.cpp
+++ b/src/ripple/rpc/handlers/Tx.cpp
@@ -22,6 +22,7 @@
 #include <ripple/app/misc/DeliverMax.h>
 #include <ripple/app/misc/NetworkOPs.h>
 #include <ripple/app/misc/Transaction.h>
+#include <ripple/app/rdb/RelationalDatabase.h>
 #include <ripple/basics/ToString.h>
 #include <ripple/net/RPCErr.h>
 #include <ripple/protocol/ErrorCodes.h>
@@ -55,6 +56,7 @@ struct TxResult
     std::variant<std::shared_ptr<TxMeta>, Blob> meta;
     bool validated = false;
     std::optional<std::string> ctid;
+    std::optional<NetClock::time_point> closeTime;
     TxSearched searchedAll;
 };
 
@@ -140,6 +142,12 @@ doTxPostgres(RPC::Context& context, TxArgs const& args)
                     *(args.hash), res.txn->getLedger(), *meta);
             }
             res.validated = true;
+
+            auto const ledgerInfo =
+                context.app.getRelationalDatabase().getLedgerInfoByIndex(
+                    locator.getLedgerSequence());
+            res.closeTime = ledgerInfo->closeTime;
+
             return {res, rpcSUCCESS};
         }
         else
@@ -269,6 +277,9 @@ doTxHelp(RPC::Context& context, TxArgs args)
         }
         result.validated = isValidated(
             context.ledgerMaster, ledger->info().seq, ledger->info().hash);
+        if (result.validated)
+            result.closeTime =
+                context.ledgerMaster.getCloseTimeBySeq(txn->getLedger());
 
         // compute outgoing CTID
         uint32_t lgrSeq = ledger->info().seq;
@@ -328,7 +339,9 @@ populateJsonResponse(
                     context.apiVersion);
             }
             response[jss::hash] = hash;
-            // TODO set `response[jss::close_time_iso]`
+            if (result.closeTime)
+                response[jss::close_time_iso] =
+                    to_string_iso(*result.closeTime);
         }
         else
         {