Estimated tax question with contractor pay

[dkh1]

My wife took a contracting job earlier this year but as I'm preparing end of year tax moves, I realized that they have not been taking out taxes (makes sense because she's a contractor) but now I'm concerned about the implications.  We had no federal estimated taxes due last year but we did have PA state taxes which I make quarterly.  Now that I know we will owe the taxes on her contracting income, should I make a payment (how do I even calculate it) before the end of the year to both the IRS and PA?  Will we be hit with a penalty regardless of what we do (pay now or just pay when we file)?  Any advice would be appreciated. 

[Anonymous_]

See https://www.irs.gov/publications/p505#en_US_2023_publink1000194559