Thanks for the reply, theOAP.
All my income is foreign source. My wife has a small amount as a sole trader. So the income is split between her Schedule C income and my gross PAYE UK income (with employer's pension contributions added). I also have some interest from a bank, about $90 for the year (UK bank), of which no foreign tax is paid. I have no other income, no US income, no capital gains etc.
For the $90 interest, I pay no UK tax. So this means it is passive income and I do not file a 1116 for it as have no credit to claim. I file a 1116 on the gross total income that is general category income. Taking my UK taxes for the year (US tax year not UK tax year), I file this on the 1116 and end up with a surplus as UK tax is higher. I have carry over I could use as well from previous year. However, I cannot reduce my tax obligation by 100%, as I have no credit to apply to the $90 interest, so the credit I can take is something like 0.9995 x total income, meaning I end up owing about $10 tax.
Now however I file AMT and I have an amount, say for a made-up example, $10,000 that is my tentative minimum tax. I work through another 1116 labelled "AMT 1116" to work out the AMTFTC. FOllowing the instructions, I have to make the line 18 be my total income + the standard deduction of around $22k, unlike the normal 1116. Therefore, when I figure the ratio of what I can apply with my FTC, it is something like 0.8. So if I multiple the $10k TMT by 0.8 to get the credit I can use, in this example that is $8000. So I end up with $10,000 (TMT) - $8000 (AMTFTC) = $2000.
So I have offset my general income by all the tax owed, I owe $10 for interest, and then I have offset 85% of my AMT meaning I have $2000 I cannot seem to apply any credit to. Therefore, I would owe in this example, $2010.
Yes I have >$10,000 tax paid to the UK that I have not used at all. This seems silly.
It also makes me wonder if is possible to elect NOT to take the "standard deduction". If I did this, I would actually be able to cover all of this tax with my foreign tax credits, as in my standard 1116 I would not be taking any deduction into account and likewise in the AMT1116 the total I would be using to determine the ratio I can apply of FTC against the TMT would be closer to 1.
Can you elect to NOT take the standard deduction? There is no downside to me - I would just take less UK tax credit over to the following years. Or do you HAVE to apply a deduction?
Many thanks in advance.