Permits for renovations

[Allison Park]

I’m looking at buying an old multifamily home built in 1900. When I walked through the house with my handyman, he said electrical and plumbing were updated recently. However, when I go to the buildings department to look up permit history, I don’t see any permits related to such work. For what it’s worth, the seller is a contractor so I’m guessing he did a lot of work himself. Is it a red flag when there are no permits on file or is it not a big deal? wondering if I should think optimistically since a seller was a contractor and probly did it right but was too lazy to pull permits or pessimistically that he cut corners because he’s a contractor and knows what he can get away with...