diff --git a/hledger-ui/Hledger/UI/UIOptions.hs b/hledger-ui/Hledger/UI/UIOptions.hs
index 4ef7bf454..26dbd9b1a 100644
--- a/hledger-ui/Hledger/UI/UIOptions.hs
+++ b/hledger-ui/Hledger/UI/UIOptions.hs
@@ -51,7 +51,7 @@ uimode =  (mode "hledger-ui" [("command","ui")]
             (argsFlag "[PATTERNS]") []){
               modeGroupFlags = Group {
                                 groupUnnamed = uiflags
-                               ,groupHidden = []
+                               ,groupHidden = hiddenflags
                                ,groupNamed = [(generalflagsgroup1)]
                                }
              ,modeHelpSuffix=[
diff --git a/hledger-web/Hledger/Web/WebOptions.hs b/hledger-web/Hledger/Web/WebOptions.hs
index d6f6411a6..a222ac011 100644
--- a/hledger-web/Hledger/Web/WebOptions.hs
+++ b/hledger-web/Hledger/Web/WebOptions.hs
@@ -75,6 +75,7 @@ webmode =
       Group
       { groupUnnamed = webflags
       , groupHidden =
+          hiddenflags ++
           [ flagNone
               ["binary-filename"]
               (setboolopt "binary-filename")
diff --git a/hledger/Hledger/Cli/CliOptions.hs b/hledger/Hledger/Cli/CliOptions.hs
index ff6c0b449..bc13e426b 100644
--- a/hledger/Hledger/Cli/CliOptions.hs
+++ b/hledger/Hledger/Cli/CliOptions.hs
@@ -12,6 +12,7 @@ module Hledger.Cli.CliOptions (
   -- * cmdargs flags & modes
   helpflags,
   detailedversionflag,
+  hiddenflags,
   inputflags,
   reportflags,
   outputflags,
@@ -112,7 +113,7 @@ helpflags = [
  ,flagNone ["version"] (setboolopt "version") "show version information"
  ]
 
--- | A hidden flag, just for the hledger executable.
+-- | A hidden flag just for the hledger executable.
 detailedversionflag :: Flag RawOpts
 detailedversionflag = flagNone ["version+"] (setboolopt "version+") "show version information with extra detail"
 
@@ -141,7 +142,7 @@ reportflags = [
  ,flagNone ["quarterly","Q"] (setboolopt "quarterly") "multiperiod/multicolumn report by quarter"
  ,flagNone ["yearly","Y"]    (setboolopt "yearly") "multiperiod/multicolumn report by year"
  ,flagReq  ["period","p"]    (\s opts -> Right $ setopt "period" s opts) "PERIODEXP" "set start date, end date, and/or report interval all at once (overrides the flags above)"
- ,flagNone ["date2"]         (setboolopt "date2") "match the secondary date instead (see command help for other effects)"
+ ,flagNone ["date2"]         (setboolopt "date2") "match the secondary date instead. See command help for other effects. (--effective, --aux-date also accepted)"  -- see also hiddenflags
 
   -- status/realness/depth/zero filters
  ,flagNone ["unmarked","U"]  (setboolopt "unmarked") "include only unmarked postings/txns (can combine with -P or -C)"
@@ -184,6 +185,13 @@ reportflags = [
 
  ]
 
+-- | Common flags that are accepted but not shown in --help,
+-- such as --effective, --aux-date.
+hiddenflags :: [Flag RawOpts]
+hiddenflags = [
+  flagNone ["effective","aux-date"] (setboolopt "date2") "Ledger-compatible aliases for --date2"
+ ]
+
 -- | Common output-related flags: --output-file, --output-format...
 outputflags = [outputFormatFlag, outputFileFlag]
 outputFormatFlag = flagReq  ["output-format","O"] (\s opts -> Right $ setopt "output-format" s opts) "FMT" "select the output format. Supported formats:\ntxt, csv, html."
@@ -262,8 +270,8 @@ addonCommandMode name = (defCommandMode [name]) {
      --  ]
   ,modeGroupFlags = Group {
       groupUnnamed = []
-     ,groupHidden = []
-     ,groupNamed = [generalflagsgroup1]
+     ,groupHidden  = hiddenflags
+     ,groupNamed   = [generalflagsgroup1]
      }
   }
 
diff --git a/hledger/Hledger/Cli/Commands/Accounts.hs b/hledger/Hledger/Cli/Commands/Accounts.hs
index 2bed0d1b5..57ac1b11e 100644
--- a/hledger/Hledger/Cli/Commands/Accounts.hs
+++ b/hledger/Hledger/Cli/Commands/Accounts.hs
@@ -43,7 +43,7 @@ accountsmode = hledgerCommandMode
   ,flagReq  ["drop"] (\s opts -> Right $ setopt "drop" s opts) "N" "flat mode: omit N leading account name parts"
   ]
   [generalflagsgroup1]
-  []
+  hiddenflags
   ([], Just $ argsFlag "[QUERY]")
 
 -- | The accounts command.
diff --git a/hledger/Hledger/Cli/Commands/Activity.hs b/hledger/Hledger/Cli/Commands/Activity.hs
index 7b4342070..78a4d023d 100644
--- a/hledger/Hledger/Cli/Commands/Activity.hs
+++ b/hledger/Hledger/Cli/Commands/Activity.hs
@@ -22,7 +22,7 @@ activitymode = hledgerCommandMode
   $(embedFileRelative "Hledger/Cli/Commands/Activity.txt")
   []
   [generalflagsgroup1]
-  []
+  hiddenflags
   ([], Just $ argsFlag "[QUERY]")
 
 barchar :: Char
diff --git a/hledger/Hledger/Cli/Commands/Balance.hs b/hledger/Hledger/Cli/Commands/Balance.hs
index 03d7a5ae0..600899549 100644
--- a/hledger/Hledger/Cli/Commands/Balance.hs
+++ b/hledger/Hledger/Cli/Commands/Balance.hs
@@ -296,7 +296,7 @@ balancemode = hledgerCommandMode
    ++ outputflags
   )
   [generalflagsgroup1]
-  []
+  hiddenflags
   ([], Just $ argsFlag "[QUERY]")
 
 -- | The balance command, prints a balance report.
diff --git a/hledger/Hledger/Cli/Commands/Checkdates.hs b/hledger/Hledger/Cli/Commands/Checkdates.hs
index 2107a8f8c..8084b447a 100755
--- a/hledger/Hledger/Cli/Commands/Checkdates.hs
+++ b/hledger/Hledger/Cli/Commands/Checkdates.hs
@@ -16,7 +16,7 @@ checkdatesmode = hledgerCommandMode
   $(embedFileRelative "Hledger/Cli/Commands/Checkdates.txt")
   [flagNone ["strict"] (setboolopt "strict") "makes date comparing strict"]
   [generalflagsgroup1]
-  []
+  hiddenflags
   ([], Just $ argsFlag "[QUERY]")
 
 checkdates :: CliOpts -> Journal -> IO ()
diff --git a/hledger/Hledger/Cli/Commands/Checkdupes.hs b/hledger/Hledger/Cli/Commands/Checkdupes.hs
index 5e7407a8b..b4d34bdf6 100755
--- a/hledger/Hledger/Cli/Commands/Checkdupes.hs
+++ b/hledger/Hledger/Cli/Commands/Checkdupes.hs
@@ -19,7 +19,7 @@ checkdupesmode = hledgerCommandMode
   $(embedFileRelative "Hledger/Cli/Commands/Checkdupes.txt")
   []
   [generalflagsgroup1]
-  []
+  hiddenflags
   ([], Nothing)
 
 checkdupes _opts j = mapM_ render $ checkdupes' $ accountsNames j
diff --git a/hledger/Hledger/Cli/Commands/Close.hs b/hledger/Hledger/Cli/Commands/Close.hs
index 389c15180..c363f3c20 100755
--- a/hledger/Hledger/Cli/Commands/Close.hs
+++ b/hledger/Hledger/Cli/Commands/Close.hs
@@ -21,7 +21,7 @@ closemode = hledgerCommandMode
   ,flagNone ["closing"] (setboolopt "closing") "show just closing transaction"
   ]
   [generalflagsgroup1]
-  []
+  hiddenflags
   ([], Just $ argsFlag "[QUERY]")
 
 close CliOpts{rawopts_=rawopts, reportopts_=ropts} j = do
diff --git a/hledger/Hledger/Cli/Commands/Import.hs b/hledger/Hledger/Cli/Commands/Import.hs
index 7ad5b71b0..7edfd9fa6 100755
--- a/hledger/Hledger/Cli/Commands/Import.hs
+++ b/hledger/Hledger/Cli/Commands/Import.hs
@@ -20,7 +20,7 @@ importmode = hledgerCommandMode
   $(embedFileRelative "Hledger/Cli/Commands/Import.txt")
   [flagNone ["dry-run"] (setboolopt "dry-run") "just show the transactions to be imported"] 
   [generalflagsgroup1]
-  []
+  hiddenflags
   ([], Just $ argsFlag "FILE [...]")
 
 importcmd opts@CliOpts{rawopts_=rawopts,inputopts_=iopts} j = do
diff --git a/hledger/Hledger/Cli/Commands/Prices.hs b/hledger/Hledger/Cli/Commands/Prices.hs
index 8a066ee15..6a9ec0ab6 100755
--- a/hledger/Hledger/Cli/Commands/Prices.hs
+++ b/hledger/Hledger/Cli/Commands/Prices.hs
@@ -19,7 +19,7 @@ pricesmode = hledgerCommandMode
   [flagNone ["costs"] (setboolopt "costs") "print transaction prices from postings"
   ,flagNone ["inverted-costs"] (setboolopt "inverted-costs") "print transaction inverted prices from postings also"]
   [generalflagsgroup1]
-  []
+  hiddenflags
   ([], Just $ argsFlag "[QUERY]")
 
 -- XXX the original hledger-prices script always ignored assertions 
diff --git a/hledger/Hledger/Cli/Commands/Print.hs b/hledger/Hledger/Cli/Commands/Print.hs
index 5e4570272..e2b4b2c56 100644
--- a/hledger/Hledger/Cli/Commands/Print.hs
+++ b/hledger/Hledger/Cli/Commands/Print.hs
@@ -37,7 +37,7 @@ printmode = hledgerCommandMode
     "show only newer-dated transactions added in each file since last run"
   ] ++ outputflags)
   [generalflagsgroup1]
-  []
+  hiddenflags
   ([], Just $ argsFlag "[QUERY]")
 
 -- | Print journal transactions in standard format.
diff --git a/hledger/Hledger/Cli/Commands/Printunique.hs b/hledger/Hledger/Cli/Commands/Printunique.hs
index 77e87b6d4..cfa9d64d7 100755
--- a/hledger/Hledger/Cli/Commands/Printunique.hs
+++ b/hledger/Hledger/Cli/Commands/Printunique.hs
@@ -15,7 +15,7 @@ printuniquemode = hledgerCommandMode
   $(embedFileRelative "Hledger/Cli/Commands/Printunique.txt")
   []
   [generalflagsgroup1]
-  []
+  hiddenflags
   ([], Nothing)
 
 printunique opts j@Journal{jtxns=ts} = do
diff --git a/hledger/Hledger/Cli/Commands/Register.hs b/hledger/Hledger/Cli/Commands/Register.hs
index 5a5692c7c..5bb47838a 100644
--- a/hledger/Hledger/Cli/Commands/Register.hs
+++ b/hledger/Hledger/Cli/Commands/Register.hs
@@ -50,7 +50,7 @@ registermode = hledgerCommandMode
      )
   ] ++ outputflags)
   [generalflagsgroup1]
-  []
+  hiddenflags
   ([], Just $ argsFlag "[QUERY]")
 
 -- | Print a (posting) register report.
diff --git a/hledger/Hledger/Cli/Commands/Registermatch.hs b/hledger/Hledger/Cli/Commands/Registermatch.hs
index fafd2dcf2..a4e30db80 100755
--- a/hledger/Hledger/Cli/Commands/Registermatch.hs
+++ b/hledger/Hledger/Cli/Commands/Registermatch.hs
@@ -18,7 +18,7 @@ registermatchmode = hledgerCommandMode
   $(embedFileRelative "Hledger/Cli/Commands/Registermatch.txt")
   []
   [generalflagsgroup1]
-  []
+  hiddenflags
   ([], Just $ argsFlag "DESC")
 
 registermatch :: CliOpts -> Journal -> IO ()
diff --git a/hledger/Hledger/Cli/Commands/Rewrite.hs b/hledger/Hledger/Cli/Commands/Rewrite.hs
index afd02f3b3..04ef55d44 100755
--- a/hledger/Hledger/Cli/Commands/Rewrite.hs
+++ b/hledger/Hledger/Cli/Commands/Rewrite.hs
@@ -29,7 +29,7 @@ rewritemode = hledgerCommandMode
   ,flagNone ["diff"] (setboolopt "diff") "generate diff suitable as an input for patch tool"
   ]
   [generalflagsgroup1]
-  []
+  hiddenflags
   ([], Just $ argsFlag "[QUERY] --add-posting \"ACCT  AMTEXPR\" ...")
 
 -- TODO regex matching and interpolating matched name in replacement
diff --git a/hledger/Hledger/Cli/Commands/Roi.hs b/hledger/Hledger/Cli/Commands/Roi.hs
index 896d65d5f..0be3fd6cf 100644
--- a/hledger/Hledger/Cli/Commands/Roi.hs
+++ b/hledger/Hledger/Cli/Commands/Roi.hs
@@ -37,7 +37,7 @@ roimode = hledgerCommandMode
     "query to select profit-and-loss or appreciation/valuation transactions"
   ]
   [generalflagsgroup1]
-  []
+  hiddenflags
   ([], Just $ argsFlag "[QUERY]")
 
 -- One reporting span, 
diff --git a/hledger/Hledger/Cli/Commands/Stats.hs b/hledger/Hledger/Cli/Commands/Stats.hs
index 1b48e195c..755c4ccb7 100644
--- a/hledger/Hledger/Cli/Commands/Stats.hs
+++ b/hledger/Hledger/Cli/Commands/Stats.hs
@@ -35,7 +35,7 @@ statsmode = hledgerCommandMode
   [flagReq  ["output-file","o"]   (\s opts -> Right $ setopt "output-file" s opts) "FILE" "write output to FILE."
   ]
   [generalflagsgroup1]
-  []
+  hiddenflags
   ([], Just $ argsFlag "[QUERY]")
 
 -- like Register.summarisePostings
diff --git a/hledger/Hledger/Cli/Commands/Tags.hs b/hledger/Hledger/Cli/Commands/Tags.hs
index 789a14e37..9ea499eb7 100755
--- a/hledger/Hledger/Cli/Commands/Tags.hs
+++ b/hledger/Hledger/Cli/Commands/Tags.hs
@@ -17,7 +17,7 @@ tagsmode = hledgerCommandMode
   $(embedFileRelative "Hledger/Cli/Commands/Tags.txt")
   [] -- [flagNone ["strict"] (setboolopt "strict") "makes date comparing strict"] -- 
   [generalflagsgroup1]
-  []
+  hiddenflags
   ([], Just $ argsFlag "[TAGREGEX [QUERY...]]")
 
 tags CliOpts{rawopts_=rawopts,reportopts_=ropts} j = do
diff --git a/hledger/Hledger/Cli/CompoundBalanceCommand.hs b/hledger/Hledger/Cli/CompoundBalanceCommand.hs
index 6bfe7fbd2..97f1662c5 100644
--- a/hledger/Hledger/Cli/CompoundBalanceCommand.hs
+++ b/hledger/Hledger/Cli/CompoundBalanceCommand.hs
@@ -108,7 +108,7 @@ compoundBalanceCommandMode CompoundBalanceCommandSpec{..} =
     ,outputFileFlag
     ]
     [generalflagsgroup1]
-    []
+    hiddenflags
     ([], Just $ argsFlag "[QUERY]")
  where
    defType :: BalanceType -> String