Why are you trying to enter your spouse's income on your own return?
Are you in a community property state?
Community property states: AZ, CA, ID, LA, NV, NM, TX, WA, WI
No, you may not add your spouse income on your tax return if your filed separate. If you live in a community property state and filed married separate, you needed to allocate both of your income on Form 8958. The form 8958 is used to determine the allocation of tax amounts between married filing status or registered domestic partner (RDP).