DataMembershipFree phone app
Guide

How to Buy Data Safely: 8 Questions to Ask Any Data Supplier

Bad data costs twice: once when you buy it, and again in wasted calls, bounced texts and complaints. Ask any supplier these eight questions before you pay.

The 8 questions

  1. Where was the data collected? First-hand from the supplier's own sites is best.
  2. When did each person opt in? Look for a time/date stamp on every record.
  3. On which website? A source URL lets you show where it came from.
  4. Which channels did they agree to? Call, SMS, email, post — it should be on the record.
  5. Is it TPS and CTPS screened? It should be, before delivery.
  6. Are the mobiles live? Ask about an HLR check.
  7. Will I get duplicates? Records you already have should be excluded, and your suppression file honoured.
  8. What can I do with it? Check the licence — usually your own marketing only, not resale.

Red flags

  • No opt-in date or source on the records.
  • "Millions of records" for very little money.
  • A supplier who can't say which channels people agreed to.
  • Sample files with half-empty columns.

How DataMembership answers them

Our data is collected first-hand on our own UK consumer sites. Every record carries the opt-in time/date stamp, URL and consent channels, is TPS/CTPS screened, has nine fields 100% populated, and never repeats records you already have. You see the price before you pay.

Questions

Should I ask for a sample?

A sample shows the layout, but the real test is whether every record has a source, an opt-in date and consent channels.

This guide is general information, not legal advice. For the full rules see the Information Commissioner's Office (ico.org.uk). Last updated October 2026.