First, you should consult with your accountant and a real estate attorney about the best way to avoid the gift tax to your father on the real estate transaction in your question.My experience which I have done in the past to address your situation is to have your father go on title to the property with you as a tenant in common where the percentages of each of your ownership interests in the home being purchased are spelled out in the deed to you. For example: you 75%, father 25 %.Under federal tax laws, your father can gift you a percentage in the home equivalent to $13,000 per year tax free. He would then gift you each year a percentage of his initial ownership equal to $13,000 by way of a grant deed for a series of years where the amount of his ownership interests is decreased and yours is increased in the home until hos ownership interests ar zero. Each year a gift tax return will need to be sent to the IRS about this.The above suggestion is based upon the assumption that your father wants to gift you the down payment for the home. If he expects repayment, he loans you the 20% for the down and you sign a promissory note for it. The note can be secured with your home. Under this scenario, your father does not go on title to the house to be purchased.Good question.