Education

Sorry, another twist on the AOTC that has lost me. TT said when maximizing the AOTC that it was a $2500 credit but I noticed in reality she didn't get that much. It was $1000 (40%) - a refundable tax credit. Why did it go this route and not give her the $2500 credit? Her total tax for the year was $7031 and she withheld $8348 from her paycheck. Thanks.