diff --git a/container/src/hledger-flow/accounts/gemini/gemini-exchange-shared.rules b/container/src/hledger-flow/accounts/gemini/gemini-exchange-shared.rules
index 7645fa0..6fc31db 100644
--- a/container/src/hledger-flow/accounts/gemini/gemini-exchange-shared.rules
+++ b/container/src/hledger-flow/accounts/gemini/gemini-exchange-shared.rules
@@ -15,7 +15,7 @@
 # You should have received a copy of the GNU General Public License
 # along with this program. If not, see <https://www.gnu.org/licenses/>.
 
-fields code_,date,type,order_type,currency_one,currency_two,amount_,cost,fees,destination,txid,direction,subaccount
+fields code_,date,type,order_type,currency_one,currency_two,amount_,cost,fees,cost_basis,destination,txid,direction,subaccount
 
 date-format %Y-%m-%d %H:%M:%S
 description %date +0000
@@ -92,12 +92,24 @@ if %type ^TRADE$
 if %order_type ^Buy$
   amount %amount_ %currency_one @@ %cost %currency_two
   comment type:%type, order_type:%order_type, order_id:%txid, tid:%code_, taxed_as:BUY
-  comment2 %date +0000,BUY,gemini,%currency_one,%amount_,%currency_two,%cost,%currency_two,%fees
+  comment2 %date +0000,BUY,gemini,%currency_one,%amount_,%currency_two,%cost_basis,%currency_two,%fees
+# TODO: HACK: re: #51, FeeCurrency and Fee are added even though cost_basis is calculated (for non-fiat fee disposal, see lib_taxes)
+
+# TODO: HACK: see #51 and respective lib_taxes work-around
+if %order_type ^Buy$
+& %currency_two ^USD$
+  comment2 %date +0000,BUY,gemini,%currency_one,%amount_,%currency_two,%cost_basis,,
 
 if %order_type ^Sell$
   amount -%amount_ %currency_one @@ %cost %currency_two
   comment type:%type, order_type:%order_type, order_id:%txid, tid:%code_, taxed_as:SELL
-  comment2 %date +0000,SELL,gemini,%currency_one,%amount_,%currency_two,%cost,%currency_two,%fees
+  comment2 %date +0000,SELL,gemini,%currency_one,%amount_,%currency_two,%cost_basis,%currency_two,%fees
+# TODO: HACK: re: #51, FeeCurrency and Fee are added even though cost_basis is calculated (for non-fiat fee disposal, see lib_taxes)
+
+# TODO: HACK: see #51 and respective lib_taxes work-around
+if %order_type ^Sell$
+& %currency_two ^USD$
+  comment2 %date +0000,SELL,gemini,%currency_one,%amount_,%currency_two,%cost_basis,,
 
 # GUSD/USD workaround (see preprocess)
 if %type ^TRADE$
diff --git a/container/src/hledger-flow/accounts/gemini/gemini-shared.bash b/container/src/hledger-flow/accounts/gemini/gemini-shared.bash
index 1340634..df3c0f5 100755
--- a/container/src/hledger-flow/accounts/gemini/gemini-shared.bash
+++ b/container/src/hledger-flow/accounts/gemini/gemini-shared.bash
@@ -111,6 +111,7 @@ function parse_transfers()
              }
            printf info_feeAmount OFS
 
+           printf OFS             # Cost-basis (N/A)
            printf $8 OFS          # Destination (info_destination)
            printf $9 OFS          # TXID (info_txHash)
 
@@ -176,6 +177,7 @@ function parse_transfers()
 
            printf OFS             # Price (N/A)
            printf OFS             # Fees (N/A)
+           printf OFS             # Cost-basis (N/A)
            printf $6 OFS          # Destination (info_destination)
            printf $7 OFS          # TXID (info_txHash)
 
@@ -250,6 +252,23 @@ function parse_trades()
          }
        printf fee_amount OFS  # Fees
 
+       # TODO: HACK: see #51 and respective lib_taxes work-around
+       # Calculate cost-basis
+       switch ($5)
+          {
+            case "Buy":
+              cost_basis=sprintf("%.8f", cost + fee_amount)
+              break
+            case "Sell":
+              cost_basis=sprintf("%.8f", cost - fee_amount)
+              break
+            default:
+              printf "FATAL: unsupported order type: " $5
+              print $0
+              exit
+          }
+       printf cost_basis OFS
+
        printf OFS      # Destination (N/A)
        printf $10 OFS  # TXID (tid)
 
@@ -309,6 +328,7 @@ function parse_earn()
        printf priceAmount OFS
 
        printf OFS  # Fees
+       printf OFS  # Cost-basis
        printf OFS  # Destination
        printf OFS  # TXID