You didn't notice your checks were more?  We have no way to know how much tax due you might owe.  You can send in an extra amount to cover some.  Or have extra taken out of your checks for the rest of the year.  See how much they take out now for 1 check and multiply it by the checks you missed.  

You can pay an estimate directly on the IRS website https://www.irs.gov/payments

Be sure to pick the right kind of payment and year.....2019 Estimate

@VolvoGirl  I started a new job, earning significantly more than I was before so I did notice but I also have never selected exempt on any of my w-4s prior so it didn't ring the bell in my head hard enough. 

I corrected it so i’ll definitely compare it to prior checks and multiply by the past weeks. At this point though, I think I just need to put some money aside and brace for tax season.  

Well try to send in some extra now.  If you owe too much on your tax return you might have a penalty for not paying in enough during the year.

@VolvoGirl how would I send in extra?

also, it’s only been wrong for ~3mths. The w4 for the job I left was correct and had the right taxes subtracted. 

I posted the link above for the IRS.  Or mail in a 4th quarter estimated payment.

Here are the blank estimate forms and instructions for federal.  You need to go to your state's website to get theirs.

https://www.irs.gov/pub/irs-pdf/f1040es.pdf

Or you can pay directly on the IRS website https://www.irs.gov/payments

Be sure to pick the right kind of payment and year.....2019 Estimate