If the terms of the financing actually say “0% interest,” then you will NOT get hit with retroactive interest because the rate being charged for the first 12 months is literally 0%. The 0% figure is a federally regulated, and lenders are very careful with it. If the terms don’t actually say “0%” but instead use language like “pay no interest for 12 months,” then you’re playing with fire. Owe so much as $1 at the end of the “interest-free” period and you’ll owe all the accrued interest.

If you must do it, get a credit card with a 15-month 0% promotion, cash back rewards and a sign-up bonus. You’ll get some money back and time to pay it off.