Hi Caroline
You are absolutely correct in saying that the extensions are just for the "time to file" and not for "time to pay". To determine how much (if any) is payable to the IRS before 15 April, you should do an estimate of your tax liability for 2002. If you had enough withholding until September (when you worked in the US) and paid enough UK taxes from September to use as Foreign tax credit (FTC) and do not have much investment income, you will not owe them any money. However I can't say this with any degree of certainty without having sight of your information for 2002. Let me know if you would like me to prepare your estimate calculation for you. If so, you can send me a note to my direct e-mail address.
I also wanted to say that all US citizens living abroad on 15 April 2003, will have an automatic extension to June 15 2003(without needing to file an extension form). But as mentioned before, this is an extension of time to file and not time to pay. If you go for the automatic extension without making a payment, and it turns out that you have a balance due to the IRs, they will charge interest from 15 April.
You will not have to pay NC taxes on your foreign source income provided that you can break residency with NC from September 2002 (when you moved to the UK). I need to know more about your situation before I can say for sure whether or not you will be able to break residency and file a part-year return in 2002. If you do not expect to file your return by April 15, you also need to file an extension form with NC and make the necessary payments then to avoid interest charges.
I hope this helps. Let me know if you have any further questions.
Helen
HT TAX
h.tanhaie@ntlworld.com
+44 208 466 9297