Credit agencies do not report income to the IRS, so there's no tax relevance. Credit agencies are not party to your obligations to the IRS at all. You can lie to credit agencies all day long if you like.

However, if you do so for the purpose of some kind of benefit, financial or otherwise, it's clearly fraud.

It's hard to remember that that's still illegal these days -- but it is, for you and for me, at least.