Yes! If you would like to make a tax-deductible contribution to Third Act, you can do so via Sustainable Markets Foundation, our 501c3 fiscal sponsor.

To send a check:

  • Please make checks out to Sustainable Markets Foundation, and write “Third Act” into the memo line. Checks can be sent by mail to:
  • Sustainable Markets Foundation (for Third Act), 40 West 37th St., Suite 1000, New York, NY 10018-7311

To send a wire transfer:

  • Please write to vanessa@thirdact.org for ACH details.
  • Grantee / Account name: Sustainable Markets Foundation—EIN number (tax ID number): 13-4188834.

Please see the next FAQ for details about donating via Donor Advised Fund. (DAFs).

Any further questions should be directed to . Thanks for supporting our work.

If you would like to donate to Third Act through your Donor Advised Fund (DAF), you can do so via Sustainable Markets Foundation, our 501c3 fiscal sponsor. Here’s the information you’ll need:

  • Grantee / Account name: Sustainable Markets Foundation
  • EIN number (tax ID number): 13-4188834.
  • Address: Sustainable Markets Foundation (for Third Act), 40 West 37th St., Suite 1000, New York, NY 10018-7311.
  • Contact name: Jay Halfon, Director, Sustainable Markets Foundation
  • Contact phone: 212-764-0521

It should be possible to include “Third Act” in a memo or Grant Designation line. Any further questions should be directed to . Thanks!

Third Act can accept gifts of stock. Please send an email to vanessa@thirdact.org for instructions about how to begin a transfer.

Yes. If you’re interested in or planning on making Third Act a beneficiary in your will or estate plans please email donations@thirdact.org.

We would be honored to work with you to create a lasting legacy in support of a fair and stable planet. You can include us as a beneficiary in your will or estate plans. A bequest is easy to arrange and is not payable until you pass away, so it does not affect assets or cash flow during the your lifetime. It is also private and revocable, since you can change provisions in the will or trust at any time, and it is not made public until death.

However we’d love to honor you by including your name among those in our Legacy Circle once you’ve decided to include us in your estate plans. Please do let us know when you’ve added us to your estate, and if you’d prefer to keep your name anonymous.

Your lawyer will need Third Act’s mailing address: Third Act Initiative, PO Box 445, Nassau, NY 12123


Third Act is a recognized partner of 1% for the Planet. If your business is interested in donating through that program, you can find us in their non-profit directory, or by writing directly to Pam Murphy at fundraising@thirdact.org.

Third Act Initiative participates in election advocacy to make sure we can “name names,” make endorsements, and come out on the sharper edge of political discourse during election cycles. It also allows us to participate in key efforts to get-out-the-vote for races that matter.

It is prohibited to use tax-deductible donations to fund this vital piece of Third Act’s work, so a portion of our staff time, software, and digital platforms must be accounted for with “c4 dollars,” or non-deductible revenue.

The easiest way is to send a check to Third Act, P.O. Box 445, Nassau, NY 12123. Please give us your name and address, as well as the name, and email/mailing address for the person you’d like to be notified of your gift. The person will only be told the amount if it involves a group of gifts (ex. Five donations were received from these people (……) in honor of Jane Doe.)

If you prefer to give online, you can donate through this Donate web page and send the above contact information to donations@thirdact.org.

Ways To Get Involved

Join our mailing list

The best way to start your third act is by signing up for our mailing list. We'll update you on our campaigns, actions you can take, and other relevant news and insights.

Take action

You have the power to be a catalyst for change. We organize different actions, online and in-person. One click can make a difference!

Find a Working Group

Working Groups are volunteer run groups organized by affinity or by geographic location. We encourage these Working Groups to carry out organizing, communication and campaigns.

Attend an event

We host workshops, community calls, and facilitated conversations each month that build skills, deepen interest, and get everyone working together on the big problems of our time.