1. Print a physical copy of your tax return and every supporting document that you used. Put it in a safe place that you will always have access to, that goes with you when you move and that is secure. Keep it for at least 4 years, or, do what I do: Keep one of those standup file folder plastic boxes and put the latest one in front and take out the oldest one when it gets a little tight. Shred the oldest one.
2. Download a pdf version of your tax return from wherever or whoever you prepared it with. Save this, and a digital copy of all your supporting documents on a secure local drive, with backup and/or a secure cloud based storage owned or controlled by YOU. The idea is to ensure you always have access to a full digital copy that is not gate-keeped by some other tax prep company. If you are savvy, you can make one big file with all the documents together.
If I did your taxes I can quickly get you access to a digital copy of the return and any of the electronic documents you sent, and many other companies can to, but you shouldn't rely on this! Take control and ensure that you always have the ability to reproduce a copy of your re
turn at a moment's notice.