Lucky Voucher is an Item in Monster Hunter World (MHW).
You can use a lucky voucher when posting a quest to add bonus rewards upon its completion.
You can toggle the use of a lucky voucher when finalizing quest selection. The voucher will be consumed as soon as you post a quest, and won't be refunded even if you cancel the quest.
Lucky Voucher Information
Lucky Vouchers are obtained once per real-life day with the Login Bonus. In the event you miss a day, you'll still get all Lucky Vouchers in the next Login Bonus. However you can only have a maximum of 5 Lucky Voucher so be sure to use them before checking the Login Bonus.
Lucky Vouchers double the amount of Zenny you get at the end of a quest, stacking with the Investigations Zenny bonus. It also allows you to get more drops as quest rewards, upping the chances of getting rare drops slightly.
Each member of a group can use one Lucky Voucher per quest. Lucky Voucher effects are NOT shared between every party member.
You can check how many Lucky Vouchers you have by going into any quest category and looking on the right border of the screen, next to the map.