2290 is usually the Income Tax Payable Account....this account should increase and decrease when you have run your payroll and submitted a payment to CRA.

Should this not be an "expense" account like the others ?

No because it is not an expense to the company. The whole amount is payable to CRA. No part of the tax from the employees is expensed to the company. You should also have a CPP and EI Payable account as well which are the amount from the employee and company amounts contributed.. So the amounts in your 3 payable accounts EI, CPP & Tax Payable are the amounts you have to send a payment to CRA every month or two times a month however this has been set up with CRA. The two expenses for the company CPP & EI stays as an expense in the books. The 3 Payable accounts will go to zero each month because it picks up the amounts from the Employees deductions and Company contribution and then reverses when you make the payment to CRA.