Co-signer / guarantor notice of default
By Justin Winter · Updated August 22, 2026
The short answer
Pursuing a guarantor for payment typically starts with a record that they were notified of the default. Send it Certified with electronic Return Receipt, $14.99 all-in: USPS records when it was mailed and when it was signed for. Preview the exact pages free. Check the guaranty terms; this template is not legal advice.
The math
The math on one certified letter.
| Option | Cost | Your time |
|---|---|---|
| paperplane, Certified + Return Receipt | $14.99, all in | About two minutes |
| At the counter | USPS fees, plus printing, an envelope and the trip | About ten minutes at the counter, plus the drive and the line |
USPS charges the same fees whoever hands the letter over. The difference is the trip, the form and the slip you keep for a year.
A signed guarantee only helps you collect if you can show you actually notified the guarantor of the default — and did so the way the guarantee agreement (or your state) requires. Telling the tenant is not the same as telling the co-signer, and a phone call or email to the guarantor is easy to deny ever happened. Certified Mail with a delivery record closes that gap.
The guarantee is a separate contract
A lease guarantee is an agreement between you and the guarantor, not between the guarantor and the tenant. Many guarantee forms include their own notice clause — some require written notice within a set number of days of the default, others require notice before you can pursue the guarantor for a specific month's rent rather than the whole remaining lease term. Read the guarantee agreement itself before you send anything; it usually controls more than general landlord-tenant law does here.
What to include
Reference the guarantee by date and the rental address it covers, describe the tenant's default in specific terms (amount owed and the period it covers, or the lease clause violated), and state plainly what you are asking the guarantor to do — pay a specific amount, cure a specific violation, or simply be aware that liability under the guarantee has been triggered. Vague language here just invites a dispute later over what the guarantor was actually told.
How it works
- Open the template, fill in the tenant's default and the guarantor's contact information.
- Pay $14.99 (Certified + Return Receipt) — the letter prints and mails the next business day.
- You get a tracking number immediately and the signed delivery record once it arrives — your proof the guarantor was notified.
This template is a tool, not legal advice. Guarantor liability, required notice, and how much a co-signer can be held responsible for all vary by state and by the specific wording of the guarantee agreement — confirm both before sending, or consult an attorney if the amount at stake is significant.
Keep reading
Questions before you send
Why not go to the post office myself?
You can, and if your time is free it costs less. USPS charges the same fees whoever hands the letter over; paperplane does not replace the post office, it replaces the trip. The mailing record comes from USPS, not from us. $12.99 covers the printing, the envelope, PS Form 3800, a USPS address check before you pay and a handoff the next business day. For a letter you already know how to send, the counter is a fine choice.
What if they refuse the letter?
USPS tracking records what happened to it, including refused or unclaimed. You still have the mailing record. Rules on what that means vary, so check with your court or an attorney if a deadline depends on it.
If something goes wrong, do I pay?
If we cannot mail the letter, the hold on your card is released and you are not charged. If a letter fails after your card is charged, you are refunded automatically and in full.
Why does the guarantor need separate notice from the tenant?
A guarantee agreement is a separate contract from the lease, and many guarantee terms — or state law — require the landlord to notify the guarantor directly, with proof, before holding them responsible for the tenant's default.
What should this letter include?
The original guarantee date, a clear description of the tenant's default, and what you are asking the guarantor to do or pay, referencing the specific terms of the guarantee agreement.
Is this legal advice?
No — it is a template. Guarantor liability and required notice procedures vary by state and by the guarantee agreement's own terms.