I've got a credit card that sends me courtesy checks with 0% interest for a year. What's to stop me from writing a check out to myself and depositing it in my high interest savings account (HSBC) for a year, earning 5% interest on it, and using that money for nothing other than paying off that cc debt? They charge a cash advance fee, but cap it off at $75, which is considerably less than the interest I would make on it if I maxed it out.

So far, I cant find a single downside to all of this, as long as I be good and dont touch the money for anything else.

Can anyone else see a downside to this?
Additional Details
Based on the responses, I'll add a few more pieces of info:

- Dont have any outstanding credit card bills to pay, other than the student loans, but at this point, im almost done anyways
- I can write the check out to cash, as I've done before to pay off other credit cards, and deposit it in my account, so that wont be an issue
- The CC company can increase my rates, but I believe the 0% checks are fixed 0% for the stated time period, but I'll double check that to make sure
- I don't use that CC to make general purchases. For that, I use my Citi Dividend Platinum Select - 5% cash back on purchases made at gas stations, supermarkets, and drug stores, 1% back everywhere else. I havent found anything better yet.


Thank you to everyone who has responded already! I found your answers very useful!