I understand that it would still be declared on a US return and 8833 attached, but if it is regular periodic distributions, why wouldn't the IRS recognise this as under Article 17.1(a)? [I know the saving clause allows the IRS to ignor 17.1(a), but why would it?]
Not to be difficult, but why should it? The saving clause means the Article doesn't apply to USCs, and therefore the IRS has the right to tax. As we've said before, the saving clause is there for a purpose: the US retains the right to tax USCs as it wants under the rules of Citizenship Based Taxation.
There are circumstances when the IRS may be somewhat slack in enforcing correct reporting. They also lack the resources to go into depth on every return filed. But if the return has an obvious 'red flag', or the return is audited, the IRS will expect everything within the return to adhere to the rules. At this point, there is no 'slackness', only IRS discretion.
I feel like I'm bursting a bubble here, but IRS agents, and more importantly - IRS computers, enforce the Code. If the revenue the taxpayer declares or reimburses is beyond the amount required, I would suggest the taxpayer may not see a refund. If the over-declaration were due to a simple mathematical mistake on the form, then the taxpayer
may see a refund.
The IRS is there to make money for the US Government. Period. Form 8833 will alert them that a stance was taken by the taxpayer. If they agree, fine. If not, they will send a bill (with penalties and interest). But, charity, good will, and logic (from the US expat point of view) are not in the Code or the agents manual. Discretion is. What about your particular return may make them forego following the rules as laid down in the Code?
An another dumb question. What exactly is meant by "basis" in the pension?
It's the amount the taxpayer (or other) has paid into the pension,
if the amount has been declared on a previous return as taxable income.
You, the US taxpayer, contribute £1,000/year to a pension for 20 years. You declare and pay US tax on the contributions, yearly. Depending on calculations, and if your contributions were the only contributions, you have a 'basis' of £20,000. BUT, there was also 'growth' in the fund throughout those 20 years, so your basis may be far, far less than 100% (or a full basis). Therefore, upon retirement, you may calculate a deduction for your contributions (a basis), but you will still have to declare some amount on a US return which will be taxable if the growth for each year was not declared previously on a US return as income and taxed accordingly in that year. There are specific IRS worksheets required for those calculations.
Again, I could be wrong.