This year the deadline falls at 7pm on September 1, with that the cut-off until player trading recommences in the new year.
As ever, it’s been a summer where names have come thick and fast in connection with Pompey.
Some of those reported talks, some have gone on to sign for the Blues with others, well, carrying less substance.
We’ve kept our ears to the ground, so here’s every player linked with Pompey so far - with some insight into the credibility of those reports.
29. Harvey Knibbs
Another of those names which always seems to be linked with Pompey. New boys Charlton were the side to land the winger from Reading, however. | Getty Images
30. Josef Bursik
The News reported Pompey were looking at the former Stoke man, who is with Belgian side Club Brugge, last month. | Getty Images
31. Minhyeok Yang
Arrived on loan for the season from Spurs earlier this month. | Simon Roe/ProSportsImages
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32. Makenzie Kirk
The News reported interest in the St Johnstone striker on August 16, with the young striker set to move on with Peterborough United keen along with Bristol Rovers. | SNS Group