I purchased a truck for $1200 for 100% business use in January 2021 but didn't place it into service until January 2022. I also bought a few parts in 2021 to prepare it for use. Can I still deduct the purchase price or repair parts for 2021? Can I use de minimis safe harbor?
No, you will wait until the vehicle is put into service before you claim expenses. After your vehicle is placed into service, you can claim actual expenses, which can include car parts or mileage. Mileage usually gives the best deduction but you can work it out both ways to see which will give you the best deduction.
Caution, if you use actual expenses in your first year, you cannot change to mileage in the second year. However, if you claim mileage in he first year, you are free to claim whatever method you choose in subsequent years.
So I am allowed to save the 2021 receipts for the purchase and repair parts for my 2022 expenses and tax return?
You can add the vehicle as an asset in 2022 and enter the cost of it, including the repairs, and you will get a depreciation deduction for it each year for 5 years. However, since it's cost is minimal, you may be better off using the standard mileage allowance of 56 cent per mile for the vehicle in lieu of actual expenses.