What is interest rate on the amount of under withheld taxes?

[Bald-Eagle1]

If the amount of withheld taxes is a lot lower than the tax amount due what is the penalty rate for the under withholding?

[SweetieJean · Accepted solution]

https://www.irs.gov/uac/newsroom/interest-rates-remain-the-same-for-the-fourth-quarter-of-2016

https://www.irs.gov/uac/things-you-should-know-about-filing-late-and-paying-penalties

[SweetieJean]

Check your state tax website if your state taxes are also underwithheld.