Cut/Paste from Marriott Bonvoy's T&Cs: https://www.marriott.com/loyalty/terms/default.mi

2.8.a. In accordance with the conditions for transferring Points as described in Section 1.6.c., a Member can transfer up to a maximum of 100,000 Points per calendar to another Membership Account as long as both Accounts are in good standing and have each been open for at least thirty (30) days with qualifying activity, ninety (90) days without qualifying activity (see 2.8.b). A Member can receive up to a maximum of 500,000 Points per calendar year from other Membership Accounts as long as the Accounts are in good standing and have each been open for at least thirty (30) days with qualifying activity, ninety (90) days without qualifying activity.