A bonus is based on your net acres and not the gross acres. For example, if you own 1/2 interest in 100 acres, then you would own 50 net mineral acres. So if the bonus is $100, then you would get $5,000 out of the $10,000 being paid for all of the acres. You do not own 100% of the minerals as some portion (fractional interest) is owned by the other family member who is leasing on your behalf. You can ask the oil company to explain how they arrived at your net mineral acres. Be sure to ask for a copy of the executed lease and keep it for your records.