Please remember this rule, and you will never be confused again about this matter: After do / does / did, you ALWAYS use the base form of the verb. (Base form = the infinitive WITHOUT the word "to.") The father DOES not HAVE a job. The father DID not HAVE a job. DOES the father HAVE a job? DID the father HAVE a job?

This is simply because the third person singular form "s" in "has" must move into "doesn't" in the negative sentence and therefore "has“ should change to "have"

"doesn't has" is wrong!

As far as I know it is bacause of the verb DO. It is something like this: If there is two auxiliary verbs in the sentence (in this case DO+HAVE) the latter one does not conjugate in person. *Sorry, can't remember the whole grammatical explanation by heart.* See examples: WITHOUT DO: The father has a job. WITHOUT DO: The father hasn't got a job. WITH DO: The father doesn't have a job. WITH DO: The father does have a job.

HAVE is used with some pronouns and plural nouns: 'I have a great English teacher.' 'You have toothpaste on your chin.' HAS Has is used with the third person singular. For example: 'She has a great personality.' 'He has a new haircut.' usually it goes like this I have = I've you have = you've we have = we've they have = They've he has = he's it has = it's since 'father' is a third person singular we use 'have'. If u are still uncertain please check the link "http://www.ecenglish.com/learnenglish/using-have-and-has" hope it helped!!!!!!!!