Reminders work, until they do not. We analysed 1.4 million expenses to find out how many nudges it takes to get a receipt, and at which point further reminders only create noise.

The three-nudge rule

Most receipts arrive after the first reminder. A second nudge recovers a further quarter. After the third, the chance of recovering the receipt barely moves, so the next step should be a consequence, not another message.

• First nudge within an hour, in chat.

• Second nudge the next morning.

• Third nudge at day seven, copying the manager.

Make the consequence light but real

A card that pauses on day thirty teaches faster than a policy document ever will.

The teams with the highest compliance did not shame anyone. They simply made the missing receipt visible and the fix a ten-second task.