diff --git a/hledger-lib/Hledger/Read/CsvReader.hs b/hledger-lib/Hledger/Read/CsvReader.hs
index 12f06bb01..cb339bfcc 100644
--- a/hledger-lib/Hledger/Read/CsvReader.hs
+++ b/hledger-lib/Hledger/Read/CsvReader.hs
@@ -452,13 +452,19 @@ validateRules :: CsvRules -> ExceptT String IO CsvRules
 validateRules rules = do
   unless (isAssigned "date")   $ ExceptT $ return $ Left "Please specify (at top level) the date field. Eg: date %1\n"
   unless ((amount && not (amountin || amountout)) ||
-          (not amount && (amountin && amountout)))
-    $ ExceptT $ return $ Left "Please specify (at top level) either the amount field, or both the amount-in and amount-out fields. Eg: amount %2\n"
+          (not amount && (amountin && amountout)) ||
+          balance)
+    $ ExceptT $ return $ Left $ unlines [
+       "Please specify (as a top level CSV rule) either the amount field,"
+      ,"both the amount-in and amount-out fields, or the balance field. Eg:"
+      ,"amount %2\n"
+      ]
   ExceptT $ return $ Right rules
   where
-    amount = isAssigned "amount"
-    amountin = isAssigned "amount-in"
+    amount    = isAssigned "amount"
+    amountin  = isAssigned "amount-in"
     amountout = isAssigned "amount-out"
+    balance   = isAssigned "balance" || isAssigned "balance1" || isAssigned "balance2"
     isAssigned f = isJust $ getEffectiveAssignment rules [] f
 
 -- parsers
diff --git a/hledger-lib/hledger_csv.m4.md b/hledger-lib/hledger_csv.m4.md
index b56b0852e..e9b5256dc 100644
--- a/hledger-lib/hledger_csv.m4.md
+++ b/hledger-lib/hledger_csv.m4.md
@@ -35,7 +35,9 @@ You can override this with the `--rules-file` option.
 If the rules file does not exist, hledger will auto-create one with
 some example rules, which you'll need to adjust.
 
-At minimum, the rules file must identify the `date` and `amount` fields. 
+At minimum, the rules file must identify the date (`date`) and 
+amount (`amount`, or `amount-in` and `amount-out`, or one of `balance`/`balance1`/`balance2`)
+fields. 
 It may also be necessary to specify the date format, and the number of header lines to skip. Eg:
 ```
 fields date, _, _, amount