It says im getting a refund of 3600, but i owe taxes. Today I received a letter that I have a certified letter at the post office from the IRS

[ThomasM · Accepted solution]

If you owe federal back taxes, then IRS can (and will) keep your refund this year and in future years until the debt is paid.  It's called an "offset."  If your debt is less than your total refund, then they will keep the debt amount and issue you a refund for the difference.

Here's a link to the IRS page discussing offsets.  It includes a contact phone number:  https://www.irs.gov/taxtopics/tc203.html.