A hatrick from striker Jason Downs and a brace from Ben Licence did the damage, with Kirk Braker completing the scoring for Ipswich Borough Council.
The IBC started strongly and early pressure had Northgate on the back foot. Tom Jackson in the centre of midfield was dictating play with his range of passing and forward runs, and Northgate were unable to get a foothold in the game.
Winger Ben Licence was a constant threat early on and in the 15th minute he put in a perfect cross for Jason Downs to head in the game's first goal from 6 yards out.
10 minutes later the score was 2-0 when centre back Jon Pritchard's long ball found Aaron Etti, whose pass inside was expertly converted by Kirk Braker.
Northgate threatened from set pieces, twice going close but on the stroke of half-time the score was 3-0 when Downs added his second goal.
At half-time Northgate had some work to do, and would've hoped for an early goal to get them back in the game. Unfortunately for them it was IBC who all but sealed victory just 3 minutes into the Second Half when the lively Ben Licence coolly slotted the ball home.
Northgate to their credit did not fold, far from it in fact as they went on to have their best spell in the game. They got the goal their effort deserved when a mistake from Pritchard allowed the striker to calmly lob the on-rushing keeper from the edge of the 18-yard box.
They had a couple of other half chances but Jason Downs put an end to any hopes of an unlikely comeback when he completed his hatrick, heading in Jackson's corner at the near post to make it 5-1.
Each team added a late goal as the game eased to a close, with Ipswich Borough Council running out 6-2 winners. Northgate tried from first minute to last but it wasn't to be their night, leaving IBC to advance to the Quarter-Finals where they can go into any game full of confidence on the back of this excellent performance.
For more information on the Ipswich Inter-Firm Cup, please visit the competition's homepage using the related link.