Hi Walter and welcome to Just Answer!
The US tax law
requires US citizens - regardless where they live - to file the tax return and report all worldwide income. As an US citizen you have certain tax responsibilities with US taxing authorities
. These responsibilities are separate from your responsibilities to the country where you are a resident.
Generally - you are required to file your tax return if your taxable income
is above $9500 in 2011 - assuming you are single.
For your ESOP distribution - you should receive should receive the form 1099-R - http://www.irs.gov/pub/irs-pdf/f1099r.pdf
The form 1099-R reports the total distribution in box 1 and the taxable amount - if any - in box 2a.
You will report these amounts on the form 1040 - www.irs.gov/pub/irs-pdf/f1040.pdf
line 15a - total distribution - from 1099-R box 1 - $90,000
line 15b - taxable part of distribution - from 1099-R box 2a - $90,000
line 61 - federal income tax withheld - from 1099-R box 4 - $18,000 - 20% withholding.
Because of your age - the distribution is not subject of 10% penalty.
Your social security benefits will be partly taxable. You will report these benefits
line 20a - total benefits - $18,000
line 20b - taxable part of benefits $18,000*85%=$15,300
So your adjusted gross income will be $90,000+$15,300=$105,300
Your actual tax liability will be determined when you prepare your tax return based on your total income, filing status, deductions
Assuming you are Single, standard deduction
, no dependents, no other deduction s or credits - your estimated federal income taxes liability would be $19950
Minus 20% that were withheld from ESOP - $18,000
and you will need to pay an additional ~$1950
Your tax liability would be less if you are eligible for additional deductions.
Please be aware that above is a very raw estimate and you need to fill your tax forms to determine exact amounts.
Let me know if you need any help or clarification.