How state tax authority identifies you are local and must pay its state tax?

I've never filed any tax before in USA until I have to file 2017 tax, for which I requested extension on Apr 17, 2018.

I moved to NC in 2015 and I guess the clue NC knows I live there is that I have a NC driver license and car registered in NC. I did not file any tax to NC and IRS before. I did not apply for business license from both states.

I started selling on eBay in NC from beginning of 2017. In the middle of 2017 my lease ended and I moved from NC to PA. For some reasons I have not changed car registration nor exchanged driver license. They are still valid in NC now.

As for the preparation for state tax filing, I find it difficult to figure out how much exactly I earned in NC and PA respectively. The income earned in NC would be estimated to be close to 20% of whole income.

I am a self-employment person with no W2. I have to file 1040 schedule C. eBay sales are my ONLY income. I got 1099K from PayPal early this year which shows ONLY my PA address (NO previous NC address). Yes, I changed my PayPal registration address from NC to PA when I moved. I wonder other than IRS if PayPal also sends 1099k to local state tax authority? If yes, it sends to PA only or both PA and NC?

For convenience, what if I only file tax with state PA for the whole income and ignore NC? Will NC go after me once I finish filing to IRS?

Get your taxes done using TurboTax

So no one knows??

Get your taxes done using TurboTax

If you accepted electronic payments for your Ebay sales, the state may have received the information that way.

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