diff --git a/CHANGELOG.md b/CHANGELOG.md
index 68c391e..91d9d82 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+# 0.6.0
+
+* Add a parser option `options.price_formula.enabled` in definition to be set to `True` for allowing to set price as formula. The formula starts with `=` and follow with valid Python code. For eg. `prestations.0.price: =1000*0.7` will yield a price of 700 on the first prestation.
+
 # 0.5.0
 
 * Add a `rounding-decimals` kwarg to `parse_invoices` and `parse_quote`, which default to `2`
diff --git a/setup.py b/setup.py
index d39c196..8bff537 100644
--- a/setup.py
+++ b/setup.py
@@ -20,7 +20,7 @@ def package_files(directory):
 
 setup(
     name="tqwgp-parser",
-    version="0.5.0",
+    version="0.6.0",
     url="https://github.com/YtoTech/talk-quote-work-getpaid-parser",
     license="AGPL-3.0",
     author="Yoan Tournade",
diff --git a/tests/test_definitions_parsing.py b/tests/test_definitions_parsing.py
index 511ab5e..62a8c2e 100644
--- a/tests/test_definitions_parsing.py
+++ b/tests/test_definitions_parsing.py
@@ -271,6 +271,25 @@ def test_parse_simple_quote_rounding():
     assert quote["price"]["vat"] == 7465.87
     assert quote["price"]["total_vat_incl"] == 44795.2
 
+def test_parse_simple_quote_rounding():
+    """
+    Prestation prices can include formulas. (opt-in)
+    """
+    definition = copy.deepcopy(TESLA_16_01_QUOTE)
+    definition["options"] = {
+        **definition.get("options", {}),
+        "price_formula": {
+            "enabled": True
+        }
+    }
+    definition["prestations"][0]["price"] = "=1000*0.3"
+    quote = parse_quote(definition)
+    checkQuote(quote)
+    assert len(quote["prestations"]) == 4
+    assert quote["prestations"][0]["total"] == 300
+    assert quote["prestations"][0]["price"] == 300
+    assert quote["price"]["total_vat_excl"] == 35300.0
+
 
 def test_parse_simple_quote_no_optional_tva():
     """
diff --git a/tqwgp_parser/parser.hy b/tqwgp_parser/parser.hy
index 11ebb40..cdfd5a2 100644
--- a/tqwgp_parser/parser.hy
+++ b/tqwgp_parser/parser.hy
@@ -27,17 +27,31 @@
           (get (parse-all-prestations (get prestation "prestations") vat-rate options prestation) 0))
         (.append sections (parse-section prestation section-prestations vat-rate options))
         (.extend all-prestations section-prestations))
-      (.append all-prestations (parse-prestation prestation section))
+      (.append all-prestations (parse-prestation prestation section options))
     )) prestation))
   (, all-prestations sections))
 
-(defn parse-prestation [prestation section]
+(defn apply-any-price-formula [price price-formula]
+  (if (and
+        (get-in price-formula ["enabled"] False)
+        (string? price)
+        (= (get price 0) "="))
+    (eval (cut price 1 None))
+    price))
+
+(defn parse-prestation [prestation section options]
   (merge-dicts [
     (parse-dict-values prestation
       ["title"]
       ["price" "quantity" "description" "batch" "optional"])
     {
-      "total" (compute-price [prestation] :count-optional True)
+      "price" (apply-any-price-formula
+        (get-default prestation "price" None)
+        (get options "price_formula"))
+      "total" (compute-price [prestation]
+        :count-optional True
+        :rounding-decimals (get options "rounding-decimals")
+        :price-formula (get options "price_formula"))
       "quantity" (get-default prestation "quantity" 1)
       "section" (get-default (if (none? section) {} section) "title" None)
       "batch" (parse-batch (get-default prestation "batch" (get-default (if (none? section) {} section) "batch" None)))
@@ -54,18 +68,23 @@
       "price" (compute-price-vat prestations
         :count-optional False
         :vat-rate vat-rate
-        :rounding-decimals (get options "rounding-decimals"))
+        :rounding-decimals (get options "rounding-decimals")
+        :price-formula (get options "price_formula"))
       "optional_price" (compute-price-vat prestations
         :count-optional True
         :vat-rate vat-rate
-        :rounding-decimals (get options "rounding-decimals"))
+        :rounding-decimals (get options "rounding-decimals")
+        :price-formula (get options "price_formula"))
       ;; TODO Normalize batch here: only set if all section prestation has same batch
       ;; (alternative: set a list of batches).
       "batch" (parse-batch (get-default section "batch" None))
       "optional" (get-default section "optional" False)
     }]))
 
-(defn compute-price [prestations [count-optional False] [rounding-decimals None]]
+(defn compute-price
+        [prestations
+          [count-optional False] [rounding-decimals None]
+          [price-formula {}]]
   """
   Parse price of a flattened list of prestations
   (actually any list with object containing a price property),
@@ -76,7 +95,7 @@
   (rounded-number
     (reduce
       (fn [total prestation]
-        (setv price (get prestation "price"))
+        (setv price (apply-any-price-formula (get prestation "price") price-formula))
         (setv add-price (and (numeric? price) (or count-optional (not (get-default prestation "optional" False)))))
         (setv prestation-total (if (numeric? price) (* price (get-default prestation "quantity" 1))))
         (cond
@@ -99,7 +118,10 @@
     (simplest-numerical-format (* (/ vat-rate 100) price))
     rounding-decimals))
 
-(defn compute-price-vat [prestations [count-optional False] [vat-rate None] [rounding-decimals None]]
+(defn compute-price-vat
+      [prestations
+        [count-optional False] [vat-rate None]
+        [rounding-decimals None] [price-formula {}]]
   """
   Compute price, as an object including VAT component, total with VAT excluded, total with VAT included ;
   from a list of objects containing a price (numerical) property.
@@ -107,7 +129,8 @@
   ;; TODO Handle price object in element list, taking total_vat_excl for the summation?
   (setv total-vat-excl (compute-price prestations
     :count-optional count-optional
-    :rounding-decimals rounding-decimals))
+    :rounding-decimals rounding-decimals
+    :price-formula price-formula))
   (if (numeric? vat-rate)
     (do
       (setv vat (if (none? total-vat-excl) None (compute-vat total-vat-excl vat-rate
@@ -209,6 +232,11 @@
       "logo" (parse-logo (get-default sect "logo" None))
     }]))
 
+(defn parse-parser-options [definition]
+  {"price_formula" {
+    "enabled" (get-in definition ["options" "price_formula" "enabled"] False)
+  }})
+
 (defn parse-quote [definition #** kwargs]
   """
   Parse and normalize a quote definition.
@@ -218,6 +246,7 @@
       "rounding-decimals" 2
     }
     kwargs
+    (parse-parser-options definition)
   ]))
   (setv vat-rate (get-default definition "vat_rate" None))
   (setv (, all-prestations sections)
@@ -235,7 +264,8 @@
       "vat_rate" vat_rate
       "price" (compute-price-vat all-prestations
         :vat-rate vat-rate
-        :rounding-decimals (get options "rounding-decimals"))
+        :rounding-decimals (get options "rounding-decimals")
+        :price-formula (get options "price_formula"))
       ;; Derive sections from all-prestations (and sections too).
       "batches" (recompose-batches all-prestations)
       "all_prestations" all-prestations
@@ -248,7 +278,8 @@
       "optional_price" (compute-price-vat all-optional-prestations
         :count-optional True
         :vat-rate vat-rate
-        :rounding-decimals (get options "rounding-decimals"))
+        :rounding-decimals (get options "rounding-decimals")
+        :price-formula (get options "price_formula"))
       "display_project_reference" (none-or-true? (get-default definition "display_project_reference" True))
     }]))
 
@@ -259,9 +290,13 @@
       ["description" "quantity"])
     {
       "quantity" (get-default line "quantity" 1)
+      "price" (apply-any-price-formula
+        (get-default line "price" None)
+        (get options "price_formula"))
       "total" (compute-price [line]
         :count-optional True
-        :rounding-decimals (get options "rounding-decimals"))
+        :rounding-decimals (get options "rounding-decimals")
+        :price-formula (get options "price_formula"))
     }
   ]))
 
@@ -290,7 +325,8 @@
       "vat_rate" (get merged-invoice "vat_rate")
       "price" (compute-price-vat lines
         :vat-rate (get merged-invoice "vat_rate")
-        :rounding-decimals (get options "rounding-decimals"))
+        :rounding-decimals (get options "rounding-decimals")
+        :price-formula (get options "price_formula"))
       "display_project_reference" (none-or-true? (get-default merged-invoice "display_project_reference" True))
     }]))
 
@@ -303,6 +339,7 @@
       "rounding-decimals" 2
     }
     kwargs
+    (parse-parser-options definition)
   ]))
   (defn parse-invoice-closure [invoice]
     (parse-invoice invoice definition options))
diff --git a/tqwgp_parser/utils.hy b/tqwgp_parser/utils.hy
index 852d9b9..ac78b9f 100644
--- a/tqwgp_parser/utils.hy
+++ b/tqwgp_parser/utils.hy
@@ -9,6 +9,9 @@
 (defn numeric? [v]
   (isinstance v (, int float)))
 
+(defn string? [v]
+  (isinstance v (, str bytes)))
+
 (defn none? [v]
   (= v None))
 
@@ -68,6 +71,18 @@
     (get value key)
     default))
 
+(defn get-in [value key-path default]
+  (setv current-key (if (= (len key-path) 0) None (get key-path 0)))
+  (if (none? current-key)
+    default
+    (if (in current-key value)
+      (if (= (len key-path) 1)
+        (get value current-key)
+        (get-in
+          (get value current-key)
+          (cut key-path 1 None)
+          default))
+      default)))
 
 ; Lists.