What this document is
Needed only if your record shows late or missed payments. Keep it short and honest: which period, the circumstances (job change, illness, didn't understand the system…), the date you paid it up, and a commitment to pay on time from now on.
What it must show
- Attach PROOF of back-payment (receipts) — more important than the explanation itself
- Date it and sign by hand
- Don't invent reasons — Immigration can cross-check pension records
Where to get it
You write it yourself (no fixed form). Support organisations usually have a template.
Notes
Filing before you have paid up is very risky — pay it off first, then file.