What are the warning signs of a tax identity-theft?

Ho can you avoid it? it's simple. File your tax return early before anyone else does it using your name. Doing so, you won't have to worry about tax theft. Even then, monitor whether or not you're receiving tax return, By filing early, usually you'll also get return early.

When the IRS flags your income tax returns as a duplicate filing.

If more than one tax return was filed using your Social Security number, then you should consider it as identity theft.

You don't receive any tax return even if you're eligible to.

I fully agree with Mabelle and SC, if you don't receive any tax returns or the IRS flags your income tax returns as a duplicate filing, consider it as a warning signs of a tax identity-theft