Asset Disposal & Gain/Loss Calculator
Retire a fixed asset cleanly: pick the asset, let AI depreciate it up to the disposal date, compute net book value and the gain or loss against proceeds, and draft the disposal journal entry — booked only after the controller approves, with the asset removed from the register and a GL-ready export.
A web tool where you import your asset register and record a disposal — sale, scrap, or trade-in. AI catches depreciation up to the disposal date, computes net book value, and calculates the gain or loss versus proceeds, then drafts the disposal journal entry that zeroes the asset's cost and accumulated depreciation, records the proceeds, and posts the gain or loss. The controller reviews and approves, and the tool exports a GL-ready journal plus an updated register with the asset retired.
Before you start
- A Supabase account (free)
- A Vercel account (free)
- An asset register export (CSV is fine) with cost, accumulated depreciation, in-service date, method, and useful life
- Claude Code or any AI coding agent
The problem this kills
An asset gets sold, scrapped, or traded in — and now you have to retire it correctly. That means catching up depreciation to the exact disposal date, reading the net book value off the register, comparing it to whatever you got for the asset, and booking an entry that zeroes out both the original cost and every dollar of accumulated depreciation while landing the difference as a gain or a loss. Get any piece wrong and the asset lingers on your register forever, or the gain/loss is off, or you keep depreciating something that left the building months ago.
Most teams do this by hand in a spreadsheet, one asset at a time, copying numbers between the fixed-asset schedule and a journal-entry template. It is fiddly arithmetic with real consequences, and the messy cases — partial disposals, trade-ins where part of the proceeds is a new asset, a disposal mid-month — are exactly where the hand-math breaks. The worst failure is silent: the entry posts, the books balance, and nobody notices the cost and accumulated depreciation didn't fully clear.
This is rules-based, high-stakes, and repetitive — the perfect shape for a small internal tool. And you do not need to be a developer to build it.
What you'll build
A simple internal web tool for asset retirements. You import your asset register once, then record a disposal: pick the asset, enter the disposal date, the proceeds, and the method (sale, scrap, or trade-in). The tool depreciates the asset up to the disposal date using its own method and convention, shows you the net book value at that moment, and computes the gain or loss against the proceeds. Then AI drafts the full disposal journal entry — debit accumulated depreciation, credit the asset cost, record the proceeds (cash or a trade-in asset), and book the gain or loss — and proves the entry balances and fully zeroes the asset.
The controller opens one screen, sees the catch-up depreciation, the net book value, the gain/loss, and the proposed entry side by side, edits anything that looks off, and clicks Approve. Only then does the tool finalize the entry, mark the asset as disposed, and produce a GL-ready journal export plus an updated asset register with the retired asset removed.
What's inside the Implementation Plan
The plan is a single file you paste into an AI coding agent. It opens by interviewing you about your business — which depreciation methods and conventions you use, exactly how your asset register is laid out and named, how you book proceeds for sales versus trade-ins, your account numbers for cost, accumulated depreciation, gain, and loss, and your nastiest edge cases like partial disposals — and then tailors the data model, the depreciation math, and every later step to your answers. This is a tool shaped around your fixed-asset process, not a generic template.
From there it walks the agent through the database schema, the asset-register import with its duplicate guards, the catch-up depreciation and net-book-value engine, the gain/loss and journal-entry drafter, the controller's review-and-approve screen, and the export of the disposal journal plus the updated register. Every step ends with a ready-to-copy prompt. Because the whole thing runs on CSV in and GL-ready CSV out, you can build and use it this afternoon even with no direct connection to your fixed-asset system.
The governance it includes (this is the point)
This touches the general ledger and removes an asset from your register, so it is built like it matters: login so only your finance team can use it, row-level security so you only ever see your own entity's assets, and a complete audit trail of every import, disposal draft, edit, approval, and export — who did what, and when. Nothing posts automatically: the disposal entry and the retirement are a draft until the controller approves, and approval is the hard human-in-the-loop gate before anything becomes a journal entry or leaves the register. Duplicate guards on the asset id mean the same asset can't be disposed twice and the same disposal can't be booked twice.
Who it's for
Staff accountants and controllers who own fixed assets and have to process retirements and disposals — sales, scrap, and trade-ins — accurately and the same way every time. If you can explain how you depreciate an asset and how you book its disposal, you can build this.
You've got this — open the plan, paste the first prompt, and let it interview you about how you retire assets.