What is this "excess accumulations in retirement account" of $850.00?

[al-jan]

I should say "What is this tax on ...?"

[MayaD]

This could happen if you didn't take the RMD(Required minimum Distribution).

Or, If you contributed more than you are allowed in a given tax year to your retirement account. 

Form 5329 is used to report additional taxes on:

• IRAs,
• Other qualified retirement plans,
• Modified endowment contracts,
• Coverdell ESAs,
• QTPs,
• Archer MSAs,
• HSAs, or
• ABLE accounts.

For more details please check DianeW777 response