I had to do one about two years ago because I got some information wrong on my 1099. Mine was a major screw up because I did not calculate my capital gains correctly. I took all my paperwork up to H&R Block and explained what I needed. Luckily I got someone there that was really familiar with the process and he walked me right through everything. The most important part is writing your explanation and making sure you keep copies and mail everything to the right places. The Federal side took almost 3 months to get approved from when I sent it to getting the letter in the mail saying my amended return was approved. On the state side I knew someone that worked there so things went through much faster. I think it was only a month. If she ends up making payments while waiting for the decision and she is owed money back afterwards they will reimburse her with interest. The thing to remember is that she needs to include the amount of interest she receives this year on next years tax return.