1. 20 minutes — find the fields that actually drive invoices
Start with a quick inventory: which fields feed your billing or renewal automation? Typical examples are unit_price/line_total, currency_code, VAT_rate (or tax_code), billing_contact, product_code/price_list and price_effective_date.
Look for where those fields live: product line items in HubSpot or Salesforce Opportunities, custom invoice objects in Marketo/Pardot flows, spreadsheets used as price lists, or middleware jobs (Zapier/Make). Note the system you consider source of truth for each field.
Record the owner for each field (who fixes it) and a simple priority: high value invoices first, recurring subscriptions second, one‑offs last.
2. 30 minutes — apply quick validations and safe fallbacks
- Currency: require ISO 4217 codes (GBP, EUR, USD); if blank, default to customer's country currency (UK → GBP) but flag anything that changes currency from the customer record.
- Price format: no negatives, sensible max (e.g. < £1,000,000 for most small businesses), max two decimal places for currency; flag zero where you expect paid invoices.
- VAT/tax: require numeric percent or recognised tax code; if blank use a conservative fallback (for UK customer_country = GB → 20%), otherwise set to 0% and flag for review.
- Effective date & pricing: require price_effective_date ≤ today; if not, pause the invoice and send to review.
- Cross-check: if product_code exists, compare line price to the product price_list and raise exceptions where mismatch > X% (choose 5–10% depending on risk).
Implement these checks where they stop the automation: field validation rules in your CRM (HubSpot/Salesforce), a small middleware step in Zapier/Make, or a scheduled script that writes a 'needs_review' flag into the record.
3. 40 minutes — human-review queue, canary invoice and one rollback step
Create a short, visible queue: a saved list or sheet that shows flagged records with reason, amount, customer, owner and a quick action (approve/fix/reject). Keep it deliberately small — start with the top 20 invoices by value or risk.
Run a canary: pick one internal test customer and one low‑value real customer to run the billing automation through manually after validations. Verify amounts, currency, VAT line and recipient before you let the full automation run. If the test fails, use your kill switch (pause the scheduled job or toggle the workflow) and void the canary invoice.
Have one clear rollback step in plain language: pause automation → snapshot offending records (export a CSV or take a saved view) → void/credit the invoice in your accounting system (Xero/Sage or your CRM object) → fix source fields → re-run the corrected invoice. Put this one‑page checklist where the team can find it and practice once with a canary.
At the end of 90 minutes you should have source‑of‑truth owners, a short list of fast validation rules and a humanised exception path that prevents noisy automations from billing the wrong amount. If you want a short workshop and a lightweight implementation plan across HubSpot, Salesforce, Marketo or Pardot, Optira can help turn this checklist into a working validation pipeline without heavy engineering.