110% prior-year safe harbor with massively lumpy income — still the cleanest path?
consultant client. 2024 AGI $380k (had a big project close). 2025 projecting $140k (more normal year). she has no W-2 withholding.
safe harbors:
- 90% of current year actual: $140k × ~22% eff rate = ~$31k estimated → quarterly $7,750
- 110% of prior year: 2024 tax was ~$95k, 110% = $104,500 → quarterly $26,125
paying 110% of prior year feels insane when current year tax will be ~$31k. she'd be overpaying by ~$73k across the year and getting it back as a refund.
i'm leaning "annualized income installment method" (Form 2210 Schedule AI) as the middle path — base each quarter on actual income through that quarter. client hates admin but it keeps cash in her account.
anyone else use AI method for lumpy clients or do you just eat the overpayment on 110% safe harbor?
2 replies
annualized income installment is the right answer here. 110% safe harbor is cash-flow punishing when the income drops sharply.
AI method mechanics: compute YTD income at each quarter-end, annualize, compute hypothetical tax, multiply by the period fraction (22.5%/45%/67.5%/90%), subtract prior installments.
software can do it (Drake, Lacerte both support) but the inputs have to be real YTD numbers. tell client to do a close-to-actual P&L each quarter.
also — if income genuinely is $140k current year, you can just pay 90% of current and eat any underpayment penalty. at $140k the penalty is ~6-7% × underpaid amount × period fraction. often cheaper than parking $73k with the IRS for 12 months.
great — AI method it is. the 90% of current approach also on the table if her Q1-Q2 actuals confirm the $140k projection.
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