It is possible to switch and borrow more with a new lender but this is subject to Loan to Income (LTI) rules by the Central Bank (CBI) i.e. no more than 3.5 times salaries or higher as an exception at a particular lenders discretion. The key consideration for you is to be happy that you can comfortably afford your repayments. From a Lenders point of view with respect to remortgaging the lenders look at two main aspects relating to Gross Income and Net Disposable Income:
Gross Income – this is made up of Salary and other variable income such as Bonus and Commission. This is the income that relates to the Central Banks LTI rules.
Net Disposable Income – this is the element that the Banks focus on looking at individuals circumstances re affordability i.e. taking into account Childcare costs or any other loans.