My employer issued a 1099NEC instead of adding it to my W2. Now IRS is saying we owe more money like we didn't claim We did claim 1099NEC as that's what was provided, but it should have been included on W2, even though taxes weren't taken out.

IRS has come back on us and said we owe more taxes because the employer provided a 1099NEC instead of adding bonus on my W2.  We did provide this information on our taxes, but used the 1099NEC, which was incorrect.  What are our options now?