OK, now the shoe is on the other foot and I need some advise.

To make a long story short, other half's parents are Taiwanese and US residents. They fly back and forth, spending a few months here, then a few months there, repeating the cycle. They understand that time outside the US does not count towards their 5 years for citizenship and that's fine.

Generally speaking, every time they re-enter the US, the inspector will scribble something on the passport around the entry stamp - like "Out x months. I-131 resident". There are a couple other words, but apparently US Immigration at SEA has a rampant penmanship problem, so we can't make out the rest of it from any of the passport entries.

So here is the issue: they have been away since the end of September, but returned a few weeks ago, so their time out was about 5 months and a couple weeks. The inspector wrote they were out 6 months, which is not true (maybe poor math skills goes along with their penmanship issues). I'm not sure if this is really an issue, but we're concerned the longer time noted by the inspector along with their back and forth travel habits might lead a future inspector to question their residency and try and take away the GCs.

Should we protest the incorrect time (it's probably logged in their computer as well), or just let it slide because it's only off by a month and 6 months is not really a bad number anyway. I know an absence exceeding 1 year can result in loss of the GC on the spot.

A couple thoughts...

1) What makes you think that 5 months, 3 weeks should be recorded as 5 months rather than 6 months?

2) What makes you think that the computer system relies on the agent rather than actually doing the math internally to know exactly how long the person was gone?

Considering that 6 months is no different than 5 months in terms of the actual impact on them I'd let it go, especially since there probably isn't anything you can do about it anyways.

I wouldn't worry. The computers record actual dates.

Thanks all

If one wanted to be paranoid (a sensible position wrt to the US CBP), one could keep all boarding passes and other paperwork showing travel times (e.g. bag tags, credit card statements, etc.). Just have a box at home and, after each trip, throw all the old documents in there (preferably after scanning them).

Just because you're paranoid doesn't mean that they aren't out to get you.