The usual moment is four to six months into a pregnancy, once the due date is confirmed and a certificate is available. Send it well before the four-week deadline, because your employer also has to complete form MB2 for your Maternity Benefit claim, a claim you should lodge at least six weeks before your leave. Many employees give notice of additional maternity leave in the same letter, which removes a second deadline from the calendar.
Plans move, though. A doctor may advise an earlier start, or you may decide to work a week or two less. The Act lets you revoke the first notification and replace it, so a short follow-up letter giving the new date at least four weeks ahead is the clean way to do it. An early birth can trigger a deadline: if the baby arrives four weeks or more before the expected week and you have not yet given notice, write within 14 days. A birth more than two weeks early also adds extra leave, which payroll needs to know about.
Two rarer situations need care. One is a newborn kept in hospital, where some mothers go back to work for a few weeks and save the rest of their leave for when the baby comes home. The other is a change of heart about additional maternity leave: the earlier notice must be revoked in writing, and the same letter can also be the return to work notice. Employers will find the contracts these letters refer to among our employment contracts and HR letters for Irish employers.