Originally Posted by Often1

I suspect that you are confusing issues in the past with respect to the use of NHS tests which were of concern, not for their accuracy, but because their cost is carried by the taxpayer. Indeed, the new scheme expressly prohibits the use of NHS tests for the test & release program.

"You cannot take a test through NHS Test & Trace to shorten your self-isolation period. You must continue to self-isolate if the result from an NHS Test & Trace test is negative."

The going forward scheme for "test out" is expressly a privately-paid system for those who wish to shorten their period of quarantine / isolation.

The question at hand is whether one may now use one of those tests for the purposes of entry to the US. The requirements for entry to the US are set by the US just as entry to the UK is set by the UK.

If one's second or third UK entry test is timely for entry to the US on return and it meets the relatively minimal requirements set by the US, it would not be for an air carrier to apply its social judgment. Thus, if one had a 10-day visit to the UK and tested out on Day 8, that Day 8 test result would be useable for one's Day 10 (or even 11) departure from the UK to the US.