What is the filing status on your tax return? Married Filing Jointly or Married Filing Separately?
If you entered the amount from box 5 from his SSA-1099 and the SS in not taxable then only the benefit amount received will be on the Form 1040 Line 6a. There will not be a taxable amount on Line 6b.
If you entered $1,800 of federal income taxes withheld as reported on the SSA-1099 then that tax payment will be included on Form 1040 Line 25b.
What calculation or input error are you seeing on the Form 1040?
