I don't know. My impression is that you don't officially lose your status until some US government official or agency confirms it. Presumably, you may not have intended to give up PR. Maybe you had a stroke or you were unable to meet the requirements through no fault of your own. But I'm speculating. I don't know.

As for the IRS, the rules are in the instructions to form 8854[1]:

> Date of termination of long-term residency.

> If you were a U.S. long-term resident (LTR), you terminated your lawful permanent residency on the earliest of the following dates.

> 1. The date you voluntarily abandoned your lawful permanent resident status by filing Department of Homeland Security Form I-407 with a U.S. consular or immigration officer.

> 2. The date you became subject to a final administrative order for your removal from the United States under the Immigration and Nationality Act and you actually left the United States as a result of that order.

> 3. If you were a dual resident of the United States and a country with which the United States has an income tax treaty, the date you commenced to be treated as a resident of that country and you determined that, for purposes of the treaty, you are a resident of the treaty country and gave notice to the Secretary of such treatment. See Regulations section 301.7701(b)-7 for information on other filing requirements if you are such an individual.

[1] https://www.irs.gov/pub/irs-pdf/i8854.pdf

EDIT: These are the rules for long-term permanent residents (8 years or more). I don't know what the rules are for other permanent residents, if there even are any. But you're probably better off if you clearly state your intent and file I-407.

Can you use the systems rules to work around the system?

My guess would be "no". The rules are interpreted by the system to benefit the system. If this means that the rules are arbitrary, capricious, and inconsistent... so be it.