Intellectual property due diligence when onboarding talent to create IP

When talent is being paid to acquire/create intellectual property, it's been my experience that the standard due diligence is to just have that party sign a contract stating they own the rights to sell what they are selling, under the terms they are selling it.

Moving beyond documenting the intellectual property to be transferred, and signing a contract, what additional due diligence might be done at low-cost?

The usual problem comes up with previous employers who claim that they own the IP. So:

(1) Get a copy of any employment agreements or invention assignment agreements he had with previous employers, and see how they impact the IP.

(2) Get an idea of WHEN things were created and compare with his employment history.

I'm not a lawyer, so this is practical experience, not professional advice.

When someone signs a contract stating they own something, they are putting themselves squarely in the firing line in the case that they don't. So this is largely a case of trying to mitigate caveat emptor ("let the buyer beware!").

Depending on the form of IP under question, more extensive due diligence is going to seek out and examine all documentation. If there are patents, where are they, what's their status, who's named, are there any loose ends? If there is code, who wrote it, where are all the contracts assigning rights, are open source licences being respected along with any other third party components?

If the primary asset being bought and sold is IP, then you can expect the scale of the due diligence to reflect the price and potential value, and the complexities of the specific category of IP.