Estimated Tax Payment Scheduler: Never Miss a Quarterly Due Date Again

The problem this kills

Quarterly estimated taxes are a quiet trap. There's no invoice, no portal nag, no boss reminding you — just four federal due dates a year, plus whatever your state and city want, each on its own calendar. Miss one and you eat an underpayment penalty that nobody asked for. So the bookkeeper keeps a sticky note, the owner keeps a different number in their head, and every quarter there's a small panic: wait, how much are we paying, to whom, and was it due last Tuesday?

The amounts are fuzzy too. Do you pay last year's safe-harbor number or this year's projection? Did the Q2 payment to the state actually go through, or did someone mean to and forget? When tax time comes, nobody can produce a clean list of what was scheduled versus what was actually paid. You don't need to live this way, and you don't need to be a developer to fix it.

What you'll build

A simple internal web tool. You enter your jurisdictions (federal, each state, any local) and either the estimated amount per quarter or your projected income so the tool can compute a safe-harbor estimate for you. The tool builds a quarterly payment calendar with the right due dates for each jurisdiction, and shows your owner or controller a clear plan: who you owe, how much, and when. The owner reviews and approves each quarter's amount before it's locked in as scheduled. As due dates approach, the tool emails reminders. When you make a payment, you record it with its confirmation number, and the tool tracks paid versus planned so you can see over- or under-payment at a glance. At the end you export a payment log and a remaining-year schedule.

What's inside the Implementation Plan

The downloadable plan is a step-by-step file you paste into an AI coding agent. It opens by interviewing you about your business — which jurisdictions you pay, whether you work from fixed estimates or projected income, your safe-harbor approach, how due dates shift for your state and city, who approves the number, and your messy edge cases — and then it tailors the data model, the calendar, and every later step to your answers. This is not a generic template; the agent reflects a short spec back to you and waits for your thumbs-up before it builds anything. From there it walks the agent through entering jurisdictions and estimates, building the calendar, the safe-harbor option, the reminder emails, the approve gate, recording payments and confirmations, and the export — each step with a ready-to-copy prompt. There's also a fallback so you can build and use the whole thing today with nothing but a spreadsheet.

The governance it includes (this is the point)

This touches money going to tax authorities, so it ships with the controls a finance team needs: login so only your team can use it, row-level security so you only ever see your own organization's tax schedule, a complete audit trail of who planned, approved, and recorded which payments and when, a hard human-approval gate so a quarter's amount isn't locked in as scheduled until the owner or controller signs off, and duplicate guards keyed on jurisdiction + quarter so the same payment can't be recorded twice. To be clear: this tool tracks and reminds — it does not move money or auto-pay. A person always makes the actual payment.

Who it's for

Small-business owners, controllers, and bookkeepers who juggle estimated taxes across more than one jurisdiction and are tired of sticky notes and quarter-end scrambles. If you can describe who you pay and when, you can build this.

You've got this — start with the plan, paste the first prompt, answer the interview, and you'll see your whole year of due dates line up the same afternoon.