WhatsApp Automation for Small Businesses in 2026: AI Replies, Lead Capture & Tiered Commissions

Your customers would rather message you on WhatsApp than fill in a contact form. That's fine at ten conversations a day. At a hundred, messages get missed, nobody knows which rep is on which deal, and at month-end somebody rebuilds the commission sheet by hand and gets it wrong. The usual answer is a $49–$499/month WhatsApp SaaS platform, priced per seat, with your customer data living in someone else's database. This post is the other answer: the same workflow on Google Sheets + Apps Script — and the one piece I see teams get wrong every single time, with the code to fix it. Where DIY WhatsApp automation actually breaks It isn't the messaging. Wiring a WhatsApp webhook into a sheet is a couple of hours of work, and I've written that build up separately — the webhook, the AI reply, and the lock that stops two reps chasing the same lead are all in Build a WhatsApp Sales Inbox in Google Sheets . I won't repeat it here. The part that breaks is the commission math . Someone writes =IF(revenue>10000, revenue*0.08, revenue*0.05) into a column, and three things kill it: A single sale spans two tiers — the formula charges the whole amount at one rate. The tiers change in July , and now every historical row recalculates at the new rate. A customer refunds in August on a sale from June, and nobody can unwind it without breaking the audit trail. So that's what this post builds: a tiered commission engine that survives rule changes and refunds. 1. Put the tiers in a table, never in a formula This is the whole trick. Make a Commission Rules tab, one row per rule: rule_id | rep_id | effective_from | effective_to | tier_1_cap | tier_1_pct | | | | | tier_2_cap | tier_2_pct | tier_3_pct --------+----------+----------------+--------------+------------+------------+----------- R1 | ALL | 2026-01-01 | | 10000 | 0.05 | | | | | 50000 | 0.08 | 0.10 R2 | rep_ayse | 2026-06-01 | | 10000 | 0.06 | | | | | 50000 | 0.09 | 0.12 rep_id is either a specific rep or ALL (the house default). Percenta