Kane scored 30 goals in 38 Premier League games for Spurs last season.
The German champions have reportedly made at least one offer for Kane, who Bild says has already agreed terms.
The deadline is a signal that Bayern are growing frustrated with the current situation, although it is not clear if they would then walk away from any deal if it was not met.
Tottenham have refused to comment.
Kane, 30, is Spurs' all-time top scorer but has one year left on his contract.
There has been no suggestion Kane would be willing to extend his contract, so if Tottenham chairman Daniel Levy opts to keep the England striker it would effectively be ending the club's last chance to cash in on their talisman.
Bayern officials met Levy earlier this week but no agreement was reached.
Tottenham open their Premier League campaign at Brentford on 13 August. Bayern begin their season with a German Super Cup meeting with RB Leipzig a day earlier.
The transfer window does not close until 1 September, but it is felt all sides would prefer a resolution before the new season begins.
-- Courtesy of BBC Sport