The Spireites were supposed to face Notts County at Meadow Lane this weekend while Town were set to host Accrington.
However, both of those clubs will now be in FA Cup action after beating Forest Green and Gillingham respectively in round three on Tuesday night.
Chesterfield and Northampton had agreed in advance that should that be the case their game should be brought forward. The match will kick-off at 3pm.
Source: Team Talk