Google Sheets Apps Script HTML / CSS / JS Vercel

IBI Tax Calculator

Custom property tax calculator for a Spanish law firm — Google Sheets backend with a standalone web app, delivered and fully paid in under 1 hour.

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Overview

A Spanish law firm specializing in real estate needed an IBI (Impuesto sobre Bienes Inmuebles) property tax calculator for the Alicante region. The tool needed to handle multiple property types (Urban, Rustic, Special) with different tax rates per municipality.

Delivered two solutions: a Google Sheets calculator with full formula automation, and a standalone HTML web app with the firm's branding — both deployed and operational within the same session.

Key Features

Municipality dropdown with 141 Alicante municipalities
Three property types with separate tax rates
Automatic IBI calculation from cadastral value
Client branding with logo integration
Google Sheets version with Apps Script deployment
Standalone HTML app — no dependencies, works offline
Mobile-responsive design
Deployed to Vercel with permanent URL

Tech Stack

Google Sheets Google Apps Script HTML5 / CSS3 Vanilla JavaScript Vercel

Outcome

All three milestones (€50 total) released immediately upon delivery. The client described the work as "Fantástico" and left a 5-star review highlighting the speed and quality. Total time from project award to full payment: under 1 hour.