Assuming this is for your 2023 tax return, several possibilities
1) Payroll took out the wrong amount from your paychecks.
2) You filled out the W-4 wrong. (Happens often, as the instructions are not really as clear as they could be)
3) You recieved a lump sum amount of money for something where taxes were not withheld and you did not pay estimated taxes. For example, if you received a bonus, or have income reported to you on a 1099-MISC or 1099-NEC and it doesn't show any taxes withheld, or if you sold something such as a house or a car, for a large amount of money and did not pay estimated taxes on that income.
