Perhaps @Joe can tell you more but the 2210 code is to track any liability on the PAYE account, it serves a slightly different purpose to the other codes in the Overheads section. 2210 holds the balance of any funds payable to HMRC between the point you run the payroll and the point you transfer the money to HMRC, during which period it’s a liability.
There’s a related post here, that may help:
http://community.quickfile.co.uk/t/does-paye-comes-off-profits/241
There’s also a more detailed ‘how to’ guide on payroll journals here:
http://community.quickfile.co.uk/t/how-do-i-enter-payroll-paye-journals-and-entries/53