@pk I skimmed this thread. While it may be true that you don't have to take a tax credit that is afforded to you (and so in this instance stop taking the credit at $300/ $600), doesn't one have to assess the unintended consequence of that action?
If TT's math is that only $309 was eligible for the foreign tax credit, then what permits the taxpayer to grab the
entire $600 from the IRS? Certainly that can't be permitted by any safe harbor. I would question (with no basis frankly) that the IRS would permit you to claim less to get a higher tax refund.
Why is this any different than a Sch C self-employed taxpayer not claiming expenses so that the resulting income is higher and the CTC and EITC tax credits are higher. That is not permitted.
