Short answer. Not the period the Labor Code prints. That article was repealed. Republic Act No. 10361 (2013), the Batas Kasambahay, now governs how a domestic worker's employment may be ended and what notice either side must give, so the notice period must be read from that Act.
What the law says
the employer or the househelper may give notice to put an end to the relationship five (5) days before the intended termination of the service
Labor Code, Article 150 — Service Of Termination Notice. Read the full provision →
The Code provision has been repealed
Article 150 of the Labor Code said that where the duration of household service was not fixed, the employer or the househelper may give notice to put an end to the relationship five (5) days before the intended termination of the service. That article was expressly repealed by Republic Act No. 10361 (2013), the Batas Kasambahay, whose repealing clause struck out the whole Labor Code chapter on the employment of househelpers. The text is kept on this site for reference only. Ending a kasambahay's employment today is governed by that Act, and the notice question has to be answered out of the Act's own termination provisions.
What to read instead
Republic Act No. 10361 sets out its own scheme for ending domestic employment: the grounds on which an employer may end it, the grounds on which the kasambahay may leave, and the notice that applies where neither side has a just cause. Check the Act's termination sections for the notice period and for what is owed on separation, rather than carrying the old five-day figure across. A notice period drawn from a repealed article is not a defence, and a household that ends an engagement on the strength of the old text may still be exposed under the Act that actually applies.
Notice is not the only thing that has to be right
Even correct notice does not make an ending lawful on its own. Under the current Act the employment sits within a framework of a written contract, registration and defined benefits, and ending it engages the wages already earned, any benefits accrued and the paperwork a departing worker is entitled to. A kasambahay who leaves is owed what she has already earned regardless of who gave the notice. Where a live-in arrangement is being ended, the practical question of when she must vacate the household is bound up with those obligations rather than separate from them.
For either side of the household
Put the notice in writing, dated, with the intended last day, and keep a copy — for both the employer and the kasambahay, the absence of a record is what turns an ordinary parting into a dispute. Keep the employment contract, the record of payments and the registration papers. If there is a disagreement about the reason for the ending, note the sequence of events while it is fresh. This page is general legal information about which law now governs, not advice on a particular household, and it cannot promise how a claim would be decided.