Clubs sometimes conclude deals at the last minute and it is not always easy for them to get everything completed and sent over by the deadline.
The deal sheet allows a club to confirm that a deal has been reached in order to allow for additional time to submit the remaining documentation.
For a deadline of 17:00 BST, the deal sheet cannot be used before 15:00 and needs to arrive fully completed before the transfer window closes.
Once the sheet arrives, clubs have got until 19:00 in which to submit the full paperwork.
But if a club are looking to complete an international transfer, they still have to comply with the FIFA Transfer Matching System (TMS) deadline of midnight.
Part 2: How do clubs begin process of completing a player transfer?
Part 3: What is the Premier League's role in the transfer process?
Part 4: What is FIFA's Transfer Matching System?
Part 5: How does the work-permit process work for transfers?
Part 6: Rules governing the third-party ownership of players
Part 7: Is a fax machine used for transfers?
Part 8: How many loans are allowed by Premier League clubs?