For date specific answers, we shouldn't get any more specific than a year. To make the tags consistent, just a single year per tag
2012 2013 2014 etc
I vote to not put instructions like "ReviewBy" because tagging should be what the information is, not what it should be.
Suggestions on How to Tag Time Sensitive Questions
- Only use years in the tags
- Tag at least the last year the answer applies
- If you can, tag the first year the answer applies
- If you are answering a question that is time sensitive, edit the question with the correct tags
Reviewing Questions That Are Time Sensitive
- Don't rely on the tags to spell out time sensitive info. Clarify in the body of the answer. (Maybe in the question too)
- If you find an Q/A that is out of date, earn free points and ask it again for the new year
- If you find an time sensitive Q/A that is of no historical value, vote to close as no longer relevant. We don't want to lead people astray, but we don't want to live exclusively in the present.
For questions that span multiple years, do the last year the answer applies if you can only tag one, do the start and end year if you can tag twice. I am saying this because having tags that span years could get out of control. I am, however, unsure of this stance and could be persuaded to change.
I see value in answers that are clear about the applicable date, even if that date is historical. While they might be periodically edited to link to a new, updated answer, I don't know why they would need to be deleted as a matter of practice. There is value in having accurate historical information.
I can also see a certain amount of damage by people who don't read, but that has to be judged on a case by case basis. Certainly tax rules from the United States that expired in 1980 don't help a ton, but tax rules from 2011 could help a person trying to catch up and not make mistakes.
I cannot speak to the specific nature of international tax rules, but from what I read here I gather they mostly work in that same way.
I imagine a scenario where two co-workers are debating some tax rule by some law, and they search on the Internet for the answer.
Alvin: 'SEE! Right there! You do get to write that off"
Simon: 'Learn to read Alvin. The answer says that write off expired last year! I WIN!"
Alvin: Darn you and your expertise money.StackExchange!