diff --git a/lib/Internal/Insert.hs b/lib/Internal/Insert.hs
index 597ebd6..a91fe9b 100644
--- a/lib/Internal/Insert.hs
+++ b/lib/Internal/Insert.hs
@@ -105,6 +105,17 @@ withDates dp f = do
 --------------------------------------------------------------------------------
 -- budget
 
+-- each budget (designated at the top level by a 'name') is processed in the
+-- following steps
+-- 1. expand all transactions given the desired date range and date patterns for
+--    each directive in the budget
+-- 2. sort all transactions by date
+-- 3. propagate all balances forward, and while doing so assign values to each
+--    transaction (some of which depend on the 'current' balance of the
+--    target account)
+-- 4. assign shadow transactions (TODO)
+-- 5. insert all transactions
+
 insertBudget :: MonadFinance m => Budget -> SqlPersistT m [InsertError]
 insertBudget Budget {budgetLabel = name, income = is, transfers = es} = do
   res1 <- mapM (insertIncome name) is