This is what I thought... was thinking of not paying any taxes, leveraging that liquid cash to invest and then just paying the taxes come tax time.... hopefully having made money with withheld taxes. Do you know what the threshold is for which you will end up owing interest? is it a percentage or a dollar amount?
The underpayment penalty is about 2% of what you owe, but it is calculated quarterly. (The penalty you owe for tax you should have paid in April will be more than the penalty you owe for tax you should have paid in September.). Then, you owe interest on all monies owed to the IRS for any reason (including underpaid taxes and penalties) at a variable rate which is currently about 5% APR.
To avoid a penalty, you must owe less than $1000 when you file your return, or the amount you paid in via withholding and estimated payments, must be at least 90% of your tax liability or 100% of your prior year tax liability.
If you are an employee then you can only stop the federal or state taxes ... there is no way to stop the FICA taxes.
Now to do that you will have to fill in a new W-4 and there are no more "claiming dependents" like in the old days and you CANNOT claim exempt because you did have a tax liability on the 2020 return and will have one on the 2021 return.
Here is the new W-4 form with instructions ... https://www.irs.gov/pub/irs-pdf/fw4.pdf
If you don't pay the estimates and your withholding isn't any of the following you will be hit with underpayment penalties.
1) 2020 balance due after withholding is less than $1000
2) withholding covers 90% of 2020 tax
3) withholding is 100% (110% if 2019 adjusted gross income is over $150,000) of 2019 tax
What you put on the W-4 has never had to match what is on the 1040 you file ... so what you enter on the W-4 is totally your choice but just know the consequences could be painful ... especially since you are thinking about "gambling" with the tax money due to the IRS ... that is as risky as gambling with rent or grocery money.