Almost every returned file we see fails on one of the same five papers, and four of them are about dates.
We keep a tally of every file that comes back to this office, our own and other people's. Over three years the list has barely changed, and it is worth publishing because four of the five cost nothing to avoid.
The medical that is older than the rule allows. A medical has a life, and a file assembled slowly can easily go in with one that expired while everybody was waiting for something else. Get the medical last, not first.
The police clearance from the wrong place. It has to come from where the person has actually lived, and for somebody who has worked in three countries that can mean three certificates. One from the country on the passport cover is not automatically enough.
The qualification that was never attested. A degree certificate is a piece of paper until the right authority in its own country has stamped it, and that stamping is the slowest single step in most files. Start it the week you decide to hire.
The passport with too little life left. A permit needs the passport to outlast it by a margin. A worker three years into a five year passport is very often the problem, and it is invisible until somebody actually counts the months.
And the name that is not the same name. A passport that says one thing, a degree that says another, and a marriage certificate that says a third is a file that will be asked about, however innocent the difference. Bring every version and we will deal with it at the front rather than by letter.
None of that is a secret and none of it is clever. It is simply what a checklist is for.