Problem: Greta and Greta's employer have both been making contributions to a qualified retirement plan for the last twenty-five years. Greta is looking forward to her retirement in a few more years and is extremely pleased to see a balance in her retirement account of $480,000 at the start of 2022. During 2022, the account earned interest, dividends, and capital gains and is now worth $500,000. Greta takes no distributions from the plan in 2022. What is the treatment of the $20,000 increase in Greta's retirement account?