Descending through a high to low QNH

[extricate]

Hi there,

Just want to get your thoughts on this. Let's say the TL is FL 100. If on descend, you switch to local QNH of say 1034 from 1013. Close to FL 100, ATC issue a last minute clearance to level off at FL100. And you switch to 1013 on levelling, the altimeter will over-read. As compared to descending from a high to low QNH?

Thanks for your time

[Dave Gittins]

Was there a question ? My only thought is that you shouldn't change altimeter setting until ATC clear you from a flight level to an altitude.