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Part 3 of 7 · Shift swap broker series ~5 min read

How eligibility is computed

The filtering is straightforward and the ordering is not, because the order of the list is what determines who gets extra hours over a year. That is a distributional decision dressed as a sort key, and it is worth making deliberately.

Key takeaways

  • Qualified reads a skills matrix, not a job title.
  • Free means not rostered and not breaking a rest rule, which is more than checking the day.
  • Overtime is computed from the whole week, not the shift.
  • The cap is a rolling window per person, and it protects them as much as the business.
  • Ordering by fewest recent extra shifts is the fairest default and it is a choice.

The four filters

The four eligibility filters applied to a shift swapA vertical chain of five steps entered by a box labelled Everyone at the site, the starting set. Step one asks whether each person is qualified for the station, reading a skills matrix of person by station. Step two asks whether they are free and legally free, checking the rota for the week either side for both rostered shifts and rest rules. Step three asks whether they stay under the overtime threshold, adding this shift to their week total against a per-contract threshold from the rules. Step four asks whether they are under their swap cap over a rolling thirty days. Step five produces a short ordered list, usually three to six people. A note says all four are arithmetic and nothing here involves judgement or a model.AWS ACCOUNTEveryone at the sitethe starting setQualified for the station?skills matrixSkillsperson x stationFree, and legally free?rostered, and rest rulesThe rotathe week either sideStays under overtime?week total + this shiftRulesthreshold per contractUnder their swap cap?rolling 30 daysA short ordered listusually three to sixAll four are arithmetic. Nothing here involves judgement or a model.
Fig 1. The four filters in order. Each removes people for a different reason and each reads something the business already maintains.
  • App integration
  • Analytics
  • People

Qualified means a station, not a job title

Two people with the same title are frequently not interchangeable: one is trained on the coffee machine and one is not, one has the forklift ticket and one does not. So the skills matrix is per person per station, and a shift carries the station it covers rather than a role name.

This is the check most likely to be missing when a business first builds something like this, because the rota shows names and times and not what each person is actually doing. Adding a station to each rota line is the prerequisite, and it is usually a morning’s work that improves the rota independently.

Free means more than not rostered

Somebody with nothing on Thursday might still be ineligible: they finish at eleven on Wednesday and start at six on Friday, and taking a Thursday evening would break a rest rule. So the check reads the week either side, not the day, and the rest rules live in the sheet because they differ by contract and by jurisdiction.

The cap protects the person

The swap cap sounds like a control on the business and is mostly a control on enthusiasm. There is always somebody who takes every available shift, and left alone they will work six weeks straight and then either burn out or make a mistake. Four extra shifts in a rolling thirty days is a reasonable default and it should be visible to them: “you are at your cap for the next nine days” is a much better message than silence.

The ordering

After filtering there are usually three to six people, and the order they are offered in is the single most consequential decision in this system, because over a year it determines who gets extra hours and therefore extra money.

Four ways to order the eligible list, and one to avoidA horizontal row of five boxes. Fewest recent swaps: the default. Nearest the site: useful for late shifts. Asked to be offered: an opt-in flag people can set. Random: genuinely defensible. Never seniority: nor who asked last time. A note says whichever you pick, publish it, because an unexplained order is assumed to be favouritism.FOUR WAYS TO ORDER, AND ONE NOT TOFewest recent swapsthe defaultNearest the sitefor late shiftsAsked to be offeredan opt-in flagRandomgenuinely defensibleNever seniorityor who asked last timeWhichever you pick, publish it. An unexplained order is assumed to be favouritism.
Fig 2. The ordering options and the one to avoid. The real requirement is not that the order is optimal but that it is stated, because an unexplained order will be assumed to be unfair.
  • App integration
  • Machine learning
  • Security & identity
  • Analytics

Fewest recent extra shifts is the default because it self-corrects: somebody who takes a swap moves down the list, and the hours spread. Random is genuinely defensible and has the advantage of being obviously not favouritism. Seniority is the one to avoid, because extra hours are money and distributing money by seniority through a scheduling system is a decision somebody should make explicitly if they are going to make it at all.

Next: how the offers actually go out.

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