How much can i pay my parents without incurring any taxes?

My Mom moved in with us about a year ago and now helps with household chores. We are married with two kids, once of them younger than 18 year of age. My mom does about $1000 worth of household chores each month, if we would get them done from someone outside our home.  I would like to have pay this amount to help her manage her expenses (Medical Insurance etc.).  She has a Green card. 

 

My question is, how much can i pay my mother for household work without having to incur any taxes for her and myself e.g. Medicare and Social Security taxes and Income tax. Can i pay her upto the deductible allowed which is $13,850.