Lead files move between funnels, suppliers, diallers and CRMs constantly, and every handoff is a chance for breakage: dates in the wrong format, phone numbers without country codes, consent lost in a renamed column. A standard CSV format removes that friction. It does not need to be complicated — it needs to be consistent, documented and validated before import, every time.
The core columns
A reliable lead file typically includes: lead id, first name, last name, phone, email, country, interest or product, source, campaign, consent status, consent date, consent wording reference, and created date. Keep column names stable and lowercase with underscores, and never rename or reorder them casually — downstream imports depend on those headers. Extra columns are fine, but the core set should always be present, even if some values are empty.
Formatting rules that prevent breakage
Use one date format everywhere, preferably ISO format (YYYY-MM-DD), and one phone format with country code. Keep text fields free of unescaped commas and line breaks, or quote them properly, and use UTF-8 encoding so names with accents survive. One lead per row, no merged cells, no summary rows, no colour-coded notes in the file — a CSV is data, not a presentation, and anything that needs a human to interpret it will break an automated import.
Consent and deduplication fields
Consent is data, not paperwork: include consent status, date and source for every row, and never import rows with missing consent into a calling system. Include a stable lead id and the source campaign so duplicates can be identified across files. A deduplication key — usually phone plus source — lets the CRM merge repeat submissions instead of creating a second record that gets called twice.
Validate before import, every time
Before importing, check row counts, required-field completeness, phone and email formats, duplicate keys and consent coverage, and reject or quarantine the file if it fails. A short validation report shared with the supplier catches problems while they are still cheap to fix. Document the format in one page, share it with every supplier and team, and version it when it changes — a standard only works when everyone uses the same one.
Want help putting this into practice for your own business? Get in touch and tell me about your project — I will give you a straight answer on the best next step.
