Timmy and Tommy’s shop undergoes several transformations as you invest in your town. To unlock each stage, you must meet specific Bell spending thresholds and a minimum number of days passed since the previous upgrade. Note that "spending" includes both items purchased and items sold to the Nooklings.
- T&T Mart: Spend 10,000 Bells at Nookling Junction and wait at least 10 days since the town was created. You must also have moved out of your tent and into a house.
- Super T&T: Spend 25,000 Bells at T&T Mart and ensure the store has been open for at least 10 days. Additionally, the Gardening Store (unlocked by pulling 30 weeds or planting 30 flowers/trees) must have been open for at least 10 days.
- T.I.Y.: Spend 50,000 Bells at Super T&T and wait 21 days after Super T&T opened. At this stage, the Gardening Store will merge with T.I.Y. to become one large building.
- T&T Emporium: This final department store stage requires spending 100,000 Bells at T.I.Y. and having the shop open for at least 30 days. Most importantly, you must pass four separate Gracie Grace Fashion Checks. Once complete, the Emporium features three floors, including a high-end boutique and the Shampoodle salon.