The Birthday Plan is for groups or members who wish to contribute to the General Service Office on their A.A. birthday. $1 per year of sobriety is suggested, but members may contribute as much as they wish up to $5,000.

https://contribution.aa.org/sca-dev-2020-1/checkout.ssp?is=checkout#login-register

Contributions may also be sent by mail to:
General Service Office
Post Office Box 2407
James A Farley Station
New York, NY 10116-2407

https://onlineliterature.aa.org/Birthday-Contribution-Envelope