my w2 includes expense reimbursement

@erik 7 expense reimbursements should not be part of reported wages on a W-2, so there should be nothing to reduce. 

Q. Should the income on the w2 be reduced by expenses i'm being reimbursed for ?

A. No. Since 2018, W-2 employees are not allowed to deduct employee expenses.  If your employer included expense reimbursement, on your W-2, then it is taxable income to you. 

But, the bigger question is: should your employer include expenses reimbursement on your W-2.   The answer is it depends on the employer's reimbursement policy.  The simplest explanation goes like this: if your employer give you a fixed "allowance" for expenses, then that allowance is taxable income to you and should be included on your W-2.  

If you account to your employer, in the form of an expense report for your exact expenses, and that's what they reimburses you for (an "Accountable plan"), then the amount is not taxable or reported on your W-2. 

If it's included on your W-2, it's taxable and you can not take a deduction, on your federal return (some states allow a deduction, on the state return).  Your only remedy is a corrected W-2 from your employer. 

You may want to talk to your employer about switching you to an "accountable plan" for expense reimbursement (it does not get added to your W-2 as taxable income), instead of a fixed allowance. On the other hand, if the allowance is generous, you may be better off paying taxes on it.

Are the expenses recorded in box 14?  That is a memo field, it is not taxable, forget about it.

Are the expenses included in your box 1 wages?  Then read below.

If the employer has an accountable plan (you prove expenses with receipts), then they should not include the reimbursement on your W-2.  You should ask them for a corrected W-2.  If they refuse, you have the option of submitting a "substitute W-2" form showing what you believe to be the accurate numbers, but this will almost certainly be questioned by the IRS.  So you want to have proof that you asked your employer, they refused, and you will need proof that you employer has an accountable expense plan.

If the expense plan is not an accountable plan, then it correct to include the payment as taxable wages, and you are not allowed to make any adjustments or deductions from that amount.