Hi, yes these are all UK bank accounts and the tax withheld is for HMRC, 20%.
To my mind, the problem with that is, until I get my ING tax statement which is for April-March, I don't actually know what the gross amount is, and also I wouldn't think that it would be accurate as it's for a different period. During the year I only see deposited into my accounts the net amount; does this mean I should calculate what £n is where 20% of £n equals all of my interest?
Multiply the net amount deposited into your account by 125% (or 5/4ths). So, a net amount of £80 is (80*1.25), or £100 gross.
Only include deposits into your account for the US tax year, 1 Jan. to 31 Dec. And yes, it is a PITA.
Don't forget, you have until June 15 to file the return.
And then, while I split my wages and taxable interest on the 1040, do I add them up as total income for the 2555-EZ, resulting in 0 on line 22 as 1040 line 21 would be (wages + interest)? Or, is it wages only on 2555-EZ, which after the calculations would go back onto line 21 as (wages) - and as I would still put something in 8a how does that affect line 22?
Yes, your question makes sense. You can not include your interest in your 2555. It is not earned income. Interest is passive unearned income. Put the interest on line 8a.
After your exemption for wages on the 2555, when you get to line 22, you will have ($100???) left from the interest. This is not a problem. As you work through the rest of the form, you will take deductions for the standard deduction (line 40), and your personal exemption (line 42). These will reduce the taxable income to $0.
The complicated way (and the way which is necessary if line 22 is over the total amount of (40+42)) is to file a Form 1116 to claim the tax paid to HMRC. For the amount you're talking about, it's probably not worth it. But, if you wish to start building up excess passive tax credits for the future, then you would file the 1116.