Payroll Tax Deposit Calendar
Build an internal tool that turns your deposit schedule and filing obligations into a live due-date calendar with tiered reminders and a sign-off log - so a late-deposit penalty never sneaks up on you again.
A private, login-protected calendar and checklist that tracks every payroll tax deposit and filing due date, nudges you with tiered reminders, and captures a signed confirmation (with reference number) when each one is done - backed by a complete compliance log you can export.
Before you start
- A free Vercel account
- A free Supabase account
- A free Resend account (for reminder emails)
- Your IRS deposit schedule (semi-weekly or monthly) and your list of filing obligations (941, 940, state withholding, state unemployment)
The problem this kills
If you self-manage payroll taxes, the calendar is your enemy. The IRS doesn't care that you were busy - miss a semi-weekly deposit by a day and you can eat a penalty of up to 10% (sometimes more) of the amount due. Multiply that across 941s, the annual 940, and your state withholding and unemployment filings, and one slipped date can cost real money.
The worst part is that the rules aren't simple. Whether a deposit is due in three days or by the 15th depends on your deposit schedule. Holidays shove due dates to the next business day. Different obligations land on different cadences. So you end up keeping it all in your head, on a sticky note, or in a spreadsheet that nobody updates - and you live with a low hum of dread that you've forgotten something.
This tool ends that. It encodes the rules once, watches the calendar for you, reminds you early and again as the deadline closes in, and makes someone actually attest "done - here's the confirmation number" so there's proof. No more guessing. No more dread.
What you'll build
A small, private web app - just for you and your team - that does five things:
- Holds your obligations and schedule. You tell it your deposit schedule (semi-weekly or monthly) and which filings you're responsible for. It stores them.
- Generates the due-date calendar. It applies the deposit-schedule rules and the next-business-day holiday shift to produce the exact upcoming due dates - no manual lookup.
- Sends tiered reminders. A heads-up several days out, a reminder the day before, and an urgent nudge on the due date itself, by email.
- Captures a human sign-off. When a deposit or filing is made, the responsible person marks it done and records the confirmation/reference number. The tool reminds; a person attests.
- Keeps a compliance log + dashboard. Every due date, every reminder, every sign-off - who did it and when - in one upcoming-due view you can glance at, plus a full log you can export to CSV.
To be crystal clear: this tool tracks deadlines. It does not file or pay anything. It's your watchdog and your paper trail, not your bank or the IRS portal.
What's inside the Implementation Plan
The plan is a single file you paste into an AI coding agent (Claude Code). The agent does the building; you answer questions and click approve.
- It starts by interviewing you about your business. Before writing a line of code, the plan makes the agent ask about your deposit schedule, exactly which obligations you carry, your states, your typical and peak liability amounts, who signs off, and your messy edge cases (mid-quarter schedule changes, multi-state, the one filing that's always different). It reads back a short tailored spec and waits for your thumbs-up. You get a tool shaped around your obligations - not a generic template you have to bend to fit.
- The full build, step by step. Database, login, the rules engine that computes due dates (including the holiday next-business-day shift), the reminder emails, the sign-off flow, the dashboard, and the CSV export - each step ends with a ready-to-copy prompt.
- The governance, baked in (see below).
- A verification checklist so you can prove to yourself it actually works before you trust it.
The governance it includes (this is the point)
This isn't a toy. The plan builds in the controls that make a tool safe to run a real compliance process on:
- Login so only your team can open it.
- Row-level security so you only ever see your own organization's data.
- A complete audit trail - who configured what, who got reminded, who signed off, and the exact timestamps.
- A human-in-the-loop sign-off gate - nothing is recorded as "deposited/filed" until a responsible person attests it and enters the confirmation reference. The tool never claims something is done on its own.
- Duplicate guards - the same obligation for the same period can't be logged twice, so your compliance record stays clean.
Who it's for
Small-business owners, controllers, and payroll admins who self-manage their tax deposits and filings - the people who currently track 941s and state withholding in their head or a spreadsheet and live in quiet fear of a late-deposit penalty. If that's you, this turns a recurring source of anxiety into a calm, checkable routine.
You've got this. Make a folder, start the agent, and paste in the first prompt - the plan takes it from there.