Monkey Money is a secondary form of currency in Bloons Tower Defense 5 and Bloons Tower Defense 5 Deluxe, along with NK Coins. Monkey Money has many uses, such as purchasing Special Agents. It is also used to buy land for Specialty Buildings, and actually building them as well. Also, you can pay Monkey Money to "rent" a Premium Upgrade for one game only. In addition, $3000 Monkey Money can be used to unlock Fast Track Mode. In Bloons Tower Defense 5 Deluxe, NK Coins are disabled and all Premium Upgrades require Monkey Money. Finally, a fee of 25-50 Monkey Money is needed to play Bloontonium Lab or Main Street.
Monkey Money can be earned by completing Tracks, opening the Treasure Chest, or completing Daily Challenges. It can also be bought with NK Coins. In Bloons Tower Defense 5 Deluxe, Monkey Money can be earned much more easily. For regular tracks, they award twice the amount of what would be in Bloons Tower Defense 5, and four times the amount for Special Missions. Additionally, $500 Monkey Money is earned every 10 ranks.
While in the menu screen, the current amount of Monkey Money is displayed in the top right corner.