Oh no.  You mean you have gone all year without having tax withheld?  You can change your W-4 with your employer right away and have them start withholding tax but that will not get you out of the hole with only a couple of months left in 2020.  You can make an estimated tax payment on the IRS site:

https://www.irs.gov/payments/direct-pay

The tax system is "pay as you go" so you might still end up with an underpayment penalty at tax time and you should expect to owe tax due---but we do not know enough about your income, dependents, filing status, etc. to know that for certain.

Try the taxcaster tool to get an idea of where you will stand at tax time.  (it is the tool for 2019 but the tax laws are so similar that it should work for this purpose)

https://turbotax.intuit.com/tax-tools/calculators/taxcaster/

And....are you in a state that has a state income tax?  You may also owe your state.

I think I set up exempt in April. I changed it back to not exempt and it offers the ability to have additional taxes withheld. Income is over 50k I’m single and no dependents. Unfortunately I’m in so much debt it’s hard to make any payments right now. 

@scottbeardsley You have been receiving paychecks since April with no federal tax withheld--and now you changed it?  Sorry---there is not an easy fix for this if you cannot afford to pay some extra tax at this time.  When you prepare your 2020 income tax return you might need to seek a payment plan for the tax you owe.  Post back for help then if you need help with how to do that.

Wont the irs charge me some sort of penalty or something? What does that entail?

Yes----you may get an underpayment penalty since you did not have enough withheld from your paychecks.

When you prepare your 2020 return it will include a form for the penalty:

https://ttlc.intuit.com/community/tax-payments/help/how-do-i-add-form-2210/00/25703

https://ttlc.intuit.com/community/tax-payments/help/why-am-i-getting-an-underpayment-penalty-if-i-m-...

https://www.irs.gov/taxtopics/tc306