When your earlier letters got no response, send one short, unambiguous final demand. It documents that you tried to resolve it (judges like that) and gives the landlord one last chance before court.

[Your full name]
[Your mailing address]
[City, State ZIP]
[Email]  ·  [Phone]

[Date]

[Landlord or property manager name]
[Landlord mailing address]
[City, State ZIP]

Re: FINAL DEMAND before legal action — security deposit
    [former rental address, unit #]

Dear [Landlord name],

I have written to you on [date(s) of earlier letters] requesting the
return of my $[deposit amount] security deposit for [former rental
address], which I vacated on [move-out date]. The statutory deadline
under [state statute citation] passed on [deadline date], and you have
not returned the deposit or provided a valid itemized statement.

This is my final demand. I am owed:

    Deposit wrongfully withheld ........ $[amount]
    Statutory penalty ($[X] x [2/3]) ... $[amount]
    [Interest / costs] ................. $[amount]
    -------------------------------------------------
    TOTAL ............................. $[total]

If I do not receive $[amount due] at my address above within [7] days of
the date of this letter, I will file a claim in [county] small claims
court for the full amount, the statutory penalty, court costs, and any
attorney's fees allowed by law, without further notice.

Sincerely,

[Signature]
[Your printed name]

Notes

Use the calculate what you’re owed guide to fill in the total, and only claim the penalty multiplier your state actually provides (see the state table).
Send certified mail, return receipt requested. Keep this and all prior letters together — you’ll attach them to your small-claims filing.

This is also your pre-suit notice in some states. Where a state requires advance written notice before filing (e.g. Colorado’s 7-day notice), word the final deadline to satisfy that requirement. Then proceed to small claims.

Final demand letter before small claims