What do you mean "not including?" Do you mean the Social Security and Medicare that was withheld from your pay in boxes 4 and 6 of your W-2? You do not get that back. Social Security and Medicare keep all of that for someday when you retire/become disabled and need to collect Social Security benefits and have medical coverage from Medicare.
Did you not have enough tax withheld in box 2? Do you owe federal tax? Or state tax due? (state tax withheld is in box 17).
If you have federal tax due you can pay by mailing your payment with the 1040V voucher, (which has the address printed on it, having the payment taken out of a designated bank account, or you can pay directly on the IRS website.
https://www.irs.gov/payments
https://ttlc.intuit.com/community/tax-payments/help/how-can-i-pay-my-federal-taxes/00/26212
https://ttlc.intuit.com/community/tax-payments/help/how-do-i-pay-my-irs-tax-due-with-a-check-or-mone...
To apply for a payment plan with the IRS
Apply Online for a Payment Plan
You must pay your state tax due using the state’s preferred method of receiving payment. For most states that will be by making a payment to the state’s own tax website, or by mailing a check or money order.
https://ttlc.intuit.com/questions/1900884-what-are-my-options-for-getting-my-state-refund-or-for-pay...
https://ttlc.intuit.com/questions/1901670-how-do-i-contact-my-state-department-of-revenue
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**
