"A", an independent researcher, has accepted a tenure-track offer* and will be starting in few months from now. "A" also has few manuscripts that are currently under review in high impact journals. Say that 1-2 manuscripts are accepted before "A" joins his/her new institution, will it be ethical/possible for "A" to contact the editors to ask them to delay publishing his/her accepted manuscript(s) to a later issue to when "A" joins his/her new institution? The rationale is that this new work won't be counted toward his/her tenure if it is to be published before he/she joins the new institution.
*This scenario is for an R1 school in the US.
Please note that "A" has discussed this issue with his/her new Dept. Chair as well as a senior mentor who serve at T&P committee (at a different school) and both advised to contact the editors for this manner.
I do not think it is either ethical or wise to try to delay the publications, anyone looking at the researcher will be equally impressed by a paper regardless of the address on it when it was published.
The principle I follow in situations such as this is "walk in the light". In other words, be open and honest about your situation and intentions with all those people who are materially involved. In this case, it would be A's new department chair (which you said A has already talked to); the editors of the journals involved (so I absolutely concur that A would need to talk with them); and any future tenure or evaluation committee that might need an explanation. If A is open and honest with these involved parties, then I see absolutely no problem with asking for a delay.
It's somewhat beside the point, but it's probably not very reasonable that A's value or quality as a researcher would be evaluated based on the whether or not a particular institution is listed on the same piece of work, but unfortunately, that's the reality of the world of academia that many of us live in. Since this question has nothing to do whatsoever with the actually quality or even perception of quality of A's work, then I don't see any deceit involved (unless A is trying to hide something). As long as A openly explains the situation to everyone involved, both now and in the future, then I think it is very reasonable to ask for a publication delay in order to meet institutional requirements. What would be unjust would be if A were denied tenure or promotion in the future simply because of a few months of advance publication of an article or two. I think it is an absolutely reasonable request to ask for a publication delay to prevent something unfortunate like that happening.
will it be ethical/possible for "A" to contact the editors to ask them to delay publishing his/her accepted manuscript(s) to a later issue to when "A" joins his/her new institution?
I would consider this action mildly unethical, since the context makes it clear that the action is taken with an intent to deceive A’s institution as to the date of publication of A’s paper. It is admittedly a small deception and falls within a gray area that some people might characterize as “gaming the system” (exploiting technical loopholes in rules and policies to gain an advantage in a way that isn’t strictly prohibited but involves minor dishonesty or pretense). Nevertheless, I do not think a person of high integrity would engage in such behavior. If I knew “A” and learned that they had done this, my opinion of them would be lessened a bit (the same goes for the department chair who advised “A” to act in this way). Conversely, I would be impressed with “A” if I learned that they had politely refused the chair’s advice. And I would think the department chair was doing their job well if they discouraged their faculty members from pursuing system-gaming measures in their approach to promotions; encouraged their faculty to expect more (both in integrity and productivity) of themselves; and lobbied with their institution’s administration to adopt healthy policies that do not create perverse incentives for misrepresentations and dishonest behavior among faculty having their performance reviewed. I realize that may be a lot to ask, but that would be the ideal. For a chair to advise their faculty to work around policies using dishonest measures may yield some short-term benefits and get the job done more or less, but it does not foster an optimal environment for the promotion of excellence.
To add a bit of context, until last summer I served for several years as a department chair at an R1 university in the US. Questions about publication dates and similar issues with promotion policies along similar lines to “A”’s question came up once in a while. I always encouraged our faculty to represent their work accurately and honestly and avoid system-gaming tricks. And on a few occasions I fought minor battles with our administration to make sure my faculty’s interests were protected in connection with what I thought were unreasonable or unhealthy policies.
I think it is wisest to follow the advice of your chair. First, the chair's advice tells me that the tenure and promotion committees care about ridiculous technicalities like this.* Second, you want to keep the chair "on your side" in the tenure and promotion process. Your chair is going to be slightly less enthusiastic about going to bat for you in a close tenure and promotion fight if you disregarded the chair's advice!
*My assumption is that the institution has both letters and quantitative metrics that must be hit to receive tenure. Letter writers generally don't care too much about when the work was done, they just care about overall research impact. However, internal metrics often only count publications while you are at the institution. For instance, you might need to hit X number of publications or get Y number of points (with more points assigned to a higher-impact journal). I am sure the chair wants to make sure these publications count toward this quantitative part of the review - our department had someone a couple of years ago who was 1 point short and didn't get tenure, even though that person was well-respected.
Honestly I don't see any moral dilemma here. If the rule is the puplication date then it is not only ethical but also smart to delay publication according to convenience. False stating the submission date is unethical, but so is asking about it (it doesn't matter, publication date does). The rules must be clear and not changed on a per case convenience (to whom?).
Notice that the submitted but not yet published manuscript was not counted in order to get the tenure track. So if it happens to be published before he/she joins the institution those will just be wasted work and an unfair advantage (luck) compared to those people that submitted later.
I concur with the majority of answers that say that asking for a delay (for this reason) is unethical at worst, tacky at best.
However, when the new excellent paper does appear in the highly rated journal the author's current (i.e. new) institution should be clearly indicated, even if that happens before the actual employment start date (which is unlikely). That way readers will know how to contact the author, and some prestige will accrue to the institution. A note saying where the author was when the work was done might be in order. I'm pretty sure the editors will agree to this change in the manuscript.