tax treshold for self employed

My wife and I are both self employed.This is my first year,can you tell me what is the combined total we can earn before tax kicks in,and is this total before or after we have written off expences,assets,etc.,
thanks on advance

You deduct expenses 'wholly and exclusively' incurred to arrive at 'profits' for year (say March 31)

First year : Actual to December (i.e. 9/12 of accounts)
Second year: Accounts to march 31 (i.e. same accounts taxed twice)
Third year: Accounting period ending in that tax year.

Thanks WizarDr,you could tell me also the combined total we can earn for the year before we have to pay tax

See [broken link removed] on revenue.ie.