The transfer window is open and several clubs have already taken the plunge into the market.
Here BBC Sport explains how the transfer window works and what moves are still permitted when the window closes.
HOW IT WORKS
The transfer window will be open between 1 and 31 January. However if the 31st is a Saturday - not the case this year - Premiership transfers can still go ahead until 1700 GMT the following Monday.
In the case of signings from abroad, international clearance has only to be requested by 1700 on 31 January. Permission can then be granted at a later date.
But all players hoping to be used in European competition must be registered with Uefa by 1100 on 2 February.
Although players were officially able to be bought and sold from New Year's Day, the
registration and administration process means clubs were not able to field new
acquisitions on 1 January or 3 January.
The Football Association insists this is not because their registration department staff were on holiday but that these were Premier League rules agreed in advance by all clubs.
It said in a statement: "Premier League rules state that documents to effect the registration of a player must be submitted by noon on the last working day before the date of the match.
"The last working day before Monday's and Tuesday's fixtures was Friday 31 December."
That meant Southampton were the first club to field new signings as Jamie Redknapp and loan import Calum Davenport featured in their game against Fulham on 5 January.
James Beattie, the £6m Everton centre-forward, and others will make debuts for their new employers in Saturday's FA Cup ties.
The transfer window will then reopen on the last day of the season.
WHAT HAPPENS WHEN THE WINDOW CLOSES
The one major caveat once the transfer window closes concerns loan signings.
Clubs can bring players in outside the window with special dispensation from the Premier League, which is generally granted only for goalkeepers in the event of an injury crisis.
An example of this was when Southampton borrowed Kasey Keller from Tottenham earlier this season.
However, no permanent signings are allowed before the end of the season when the transfer window reopens once more.