diff --git a/packages/taler-util/src/time.ts b/packages/taler-util/src/time.ts
index 8b4f4cac3..6ada13e25 100644
--- a/packages/taler-util/src/time.ts
+++ b/packages/taler-util/src/time.ts
@@ -23,15 +23,40 @@
  */
 import { Codec, renderContext, Context } from "./codec.js";
 
+declare const flavor_AbsoluteTime: unique symbol;
+declare const flavor_TalerProtocolTimestamp: unique symbol;
+declare const flavor_TalerWalletDbTimestamp: unique symbol;
+
 export interface AbsoluteTime {
   /**
    * Timestamp in milliseconds.
    */
   readonly t_ms: number | "never";
+
+  readonly _flavor?: typeof flavor_AbsoluteTime;
 }
 
 export interface TalerProtocolTimestamp {
+  /**
+   * Seconds (as integer) since epoch.
+   */
   readonly t_s: number | "never";
+
+  readonly _flavor?: typeof flavor_TalerProtocolTimestamp;
+}
+
+export interface TalerWalletDbTimestamp {
+  /**
+   * Seconds (as integer) since epoch.
+   */
+  readonly t_s: number | "never";
+
+  /**
+   * Optional microsecond offset (non-negative integer).
+   */
+  readonly off_us?: number;
+
+  readonly _flavor?: typeof flavor_TalerWalletDbTimestamp;
 }
 
 export namespace TalerProtocolTimestamp {