Safe Harbor on Estimated Taxes: Avoid the Underpayment Penalty (11.4.2)

Safe harbor is a guarantee from the IRS. Pay this amount across these four installments and they cannot charge you an underpayment penalty regardless of what you actually owe in April. The guarantee is in the tax code. Two formulas qualify. One is usually better for your situation, and the threshold between them is whether prior-year AGI crossed $150,000. The penalty itself is small in dollar terms. The discipline of safe harbor isn't about the penalty — it's about the protection it gives you to stop tracking in-period income entirely and still land safe in April. Sits inside Unit 11.4 quarterly estimated taxes. Chapters: 0:00 Safe Harbor: The IRS Guarantee 0:47 What the Guarantee Actually Covers 1:37 Three Formulas and the $150K Threshold 2:34 Choosing the Right Formula by Year 3:25 The Penalty Is Small but Avoidable 4:16 Cash Flow Shapes: Option A vs Option B 5:10 State Safe-Harbor Rules Vary 5:58 Compute Your Number Before Leaving In this lesson: • What safe harbor actually guarantees — pay this amount in these four installments and the underpayment penalty does not apply regardless of the April balance • The three formulas — 100% of prior-year tax (line 24 of last year's 1040), 110% of prior-year when prior-AGI exceeded $150K single/MFJ, 90% of current-year actual for Year One with no prior return • Selection logic by situation — Year One uses the 90% rule, growing income years use prior-year and accept a larger April balance, declining income years switch to 90%-of-current • Underpayment penalty math — federal short-term rate plus 3 points, 7-8% annualized at recent rates; $5K underpayment for six months runs $175-$200 • Worked example with $12K Year One tax and $16K Year Two projected — Option A (prior-year) vs Option B (90% current) shape cash flow differently with identical penalty protection • State safe-harbor rules vary — some mirror federal, some require different percentages, some accept only 90%-of-current; verify your state Department of Revenue instructions • Action: compute your safe-harbor number, divide by four, compare against what you've already paid, true up at the next quarter About the course Setting Up Your Coaching Practice is the entry course in The Practitioner Series — async ICF Continuing Coach Education specializations for credentialed and pre-credentialed coaches. 21 modules, 171 videos, fully self-paced. Covers everything from forming the entity through year-one tax filing. Framework: Coach as Founder — the identity shift from a coach who is starting a business to a founder who builds the operational foundation a coaching practice runs on. ICF CCE eligible: ~20 hours (4 Core Competency + 16 Resource Development) — bracket pending Phase 10 submission. ▶ Next lesson: Self-Employment Tax Explained: The 15.3% Coaches Pay →    • Self-Employment Tax Explained: The 15.3% C...   Full course (Tandem Coaching Academy): https://community.tandemcoaching.acad... More from Tandem: https://tandemcoach.co Coaching industry data: https://tandemcoach.co/coaching-indus... #CoachingPractice #NewCoach #ICF #CoachAsFounder #PractitionerSeries #TandemCoaching