If My employer pays my income taxes to irs, why am I getting a penalty for underpayment?

[richnoyes]

You are responsible for the payment of your taxes.  You could overclaim exemptions to cause your employer to underpay what you will need to pay.  That is not your employer's responsibility.

Also, if you have additional income, you may be required to file quarterly estimates.

[MayaD]

Are you having enough taxes withheld from your paychecks? The IRS levies underpayment penalties if you don't withhold or pay enough tax on income received during each quarter.

Check your withholding often and adjust it when your situation changes. You can increase your withholding by filling out a new Form W-4 and giving it to your employer.

Generally, most taxpayers will avoid this penalty if they either owe less than $1,000 in tax after subtracting their withholding and refundable credits, or if they paid withholding and estimated tax of at least 90% of the tax for the current year or 100% of the tax shown on the return for the prior year, whichever is smaller.

Underpayment of estimated tax by individuals penalty