Explain a rule change to clients

I work in marketing at a financial advice firm. Help me explain a rule or industry change to our clients in plain English.

Context: Clients hear about a Budget or a pension change on the news and worry about their own plans. They value an adviser who explains it early and without alarm.

Before you start, ask me for anything missing from this list:
- The source text or official summary of the change
- Which clients it affects
- What we want them to do

Then:
1. Say what is changing and when, using only the source I gave you.
2. Say who is affected and who is not.
3. Say what the reader should do now, and what can wait.
4. Keep general information separate from advice.

Give me:
- A headline
- An explainer of 300 to 450 words
- A three-line version for email or social

Rules:
- Use only the facts I give you. Where something is missing, write [detail needed]. Never invent a number, a name, a quote or a source.
- Give general financial information only. Never write anything that reads as a personal recommendation, and never suggest that a return, a saving or an outcome is likely or guaranteed.
- Write in plain English, in our voice if I have given you a sample.
- Do not tell me what the rules or regulations say. If something may be restricted, flag it and I will check.

Finish with a list headed "Check before this goes out". Include these, plus anything else our compliance officer or whoever approves our financial promotions should see:
- Every date, rate and allowance against the official source
- Whether the change is confirmed, or still a proposal
- An adviser's review of the 'what to do now' section