diff --git a/69.md b/69.md
index 1750b620..1a098e8f 100644
--- a/69.md
+++ b/69.md
@@ -23,6 +23,7 @@ A poll event:
 * MUST contain a `poll_options` tag, containing a serialized key-value array of vote options, formatted as below
 * MUST include at least 2 voting options, each with its own unique description string
 * SHOULD specify a `closed_at` time:
+  * when specified, MUST include a valid [`ots` tag](03.md), proving original poll publishing time
   * a `closed_at` value of less than or equal to the `created_at` field indicates a poll SHOULD NOT be closed.
 * MAY specify a `value_maximum` satoshi value for zapped votes to be included in the tally
 * MAY specify a `value_minimum` satoshi value for zapped votes to be included in the tally
@@ -45,6 +46,7 @@ A poll event:
     ["consensus_threshold", "required percentage to attain consensus <0..100>"],
     ["closed_at", "unix timestamp in seconds"],
   ],
+  "ots": <base64-encoded OTS file data>
   "content": <primary poll description string>,
   "sig": <64-bytes hex of the signature of the sha256 hash of the serialized event data, which is the same as the "id" field>
 }
@@ -61,14 +63,18 @@ The zap request event (kind `9734`):
   * MUST include the same primary hosting relay URL in the `p` tag as is specified in the `e` tag
 * MUST include exactly 1 `poll_option` tag
 * MUST reference the vote option by its corresponding integer `n`, chosen from the original poll event's key-value array of predefined `polling_options`
+* MUST include a valid `ots` tag, if the original poll event specifies a `closed_at` time
 
 ```json
+...
 "tags": [
   ["e", <32-bytes hex of the id of the original poll event>, <primary poll host relay URL>],
   ["p", <32-bytes hex of the key>, <primary poll host relay URL>],
   ["poll_option", "n"],
   ...
-]
+],
+"ots": <base64-encoded OTS file data>
+...
 ```
 
 ## Poll outcome
@@ -84,8 +90,9 @@ A tallying client:
 * MUST ONLY tally zaps sent to the poller's `p` key
 * MUST ONLY include zap amounts less than or equal to `value_maximum`, if specified
 * MUST ONLY include zap amounts greater than or equal to `value_minimum`, if specified
-* if a valid `closed_at` time is specified, clients:
-  * MUST NOT tally late votes received after `closed_at` time
+* if a `closed_at` time is specified, clients:
+  * MUST ONLY tally zaps including a valid `ots` tag indicating a sent time greater than or equal to the original poll event's `ots` time  
+  * MUST ONLY tally zaps including a valid `ots` tag indicating a sent time less than or equal to `closed_at` time
 
 Additionally, a tallying client:
 * MUST display the distribution percentages, from the tally total, for each vote option tally