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.
25. Grady Diangana
The News reported there was no interest in the winger last month, with talk of a move to Saudi Arabia now being reported. | Getty Images
26. Luke Le Roux
Pompey brought in the South African from Swedish strugglers IFK Varnamo last month, after he was spotted days before the deal was announced. Photo: Simon Roe
27. Florian Bianchini
Pompey's first loan signing of the summer joined on the final day of last month from Swansea, with whispers of interest in the Frenchman in the air. Photo: Alun Roberts
28. Krystian Bielik
Pompey were keen in the Polish international, with the Polish international favouring staying in the midlands and moving from Birmingham to West Brom. | Getty Images