The Credit Ledger 
If you have read a broad SoFi-versus-Ally review, you have probably seen the savings sub-accounts mentioned in a single sentence and then dropped. That is a missed opportunity, because the way each bank lets you carve up a savings balance is exactly where a real sinking-fund system lives or dies. This is the head-to-head those reviews bury: SoFi Vaults against Ally Buckets, judged on the features that actually matter when you are funding a car-repair pot, a holiday pot, and an annual-insurance pot at the same time.
What sinking funds need from a savings account
A sinking fund is money you set aside on purpose for a known future expense, such as property taxes, a vacation, or a new laptop. It is different from an emergency fund, which exists for the unexpected. The Consumer Financial Protection Bureau notes that money left in a savings account earns compound interest over time, which is exactly the job a sinking fund asks of it: hold money you do not plan to spend right away while it keeps growing.
The features that make sinking funds easy to run are simple: enough sub-accounts to give each goal its own home, automation that funds those goals without daily effort, and a clear rate so you know what your patience is buying. SoFi and Ally both attack this with named sub-accounts, but they do it differently.
Number of vaults vs buckets
Both banks let you split one savings balance into named compartments. SoFi calls them Vaults; Ally calls them Buckets. The headline difference is count.
Ally allows a larger number of buckets per savings account, which suits people who like granular systems with a separate pot for every category. SoFi allows a smaller but still generous number of Vaults, which is plenty for most households running five to ten goals. Because caps are adjusted from time to time, confirm the current numbers on each issuer’s help pages before you commit a complex system to one platform.
For practical purposes, ask yourself how many goals you actually track. If you run a dozen or more micro-categories, Ally’s higher ceiling is the safer bet. If you run a tidy handful, either bank has room to spare.
Automation: round-ups vs Surprise Savings
This is where the two diverge most, and where your habits should drive the choice.
SoFi: round-ups
SoFi’s signature automation is round-ups, which rounds up debit-card purchases and sweeps the spare change into savings. It is passive and tied to spending, so the more you swipe, the more you save. That works well if SoFi is your everyday spending account.
Ally: three boosters
Ally offers three savings boosters rather than one. Recurring transfers move a set amount on a schedule you choose. Round-ups track your Ally spending account and round transactions to the nearest dollar. Surprise Savings analyzes your linked checking for money it considers safe to move, then transfers it automatically. That third option is the standout: it funds goals from cash-flow slack rather than from spending, which is a fundamentally different lever.
If you want automation that grows savings without depending on how much you spend, Ally’s Surprise Savings has no direct SoFi equivalent.
Per-bucket APY and recurring transfers
Here is the most common misconception, and it applies to both banks equally: you do not earn a separate interest rate per vault or per bucket. Both products pay one account-wide APY on your total savings balance, and the compartments are organizational only. Splitting $10,000 into ten goals earns the same interest as leaving it in one pile. Treat APY as an account-level decision, then organize freely. Always verify the current APY against the issuer’s terms, since rates move.
On recurring transfers, both banks let you schedule automatic deposits. Ally builds recurring transfers in as a named booster you can point at a specific bucket. SoFi supports scheduled transfers into Vaults as well. For a disciplined “pay yourself first” sinking-fund plan, both will do the core job; the difference is how directly the tool maps a recurring deposit to a single goal.
Decision table by use case
| Your situation | Better fit | Why |
|---|---|---|
| You track many granular goals (10+) | Ally Buckets | Higher bucket ceiling for complex systems |
| You want savings to grow from cash-flow slack | Ally (Surprise Savings) | Funds goals from safe-to-save cash, not spending |
| You spend daily on the bank’s debit card | Either, slight edge SoFi | Round-ups capture spare change passively |
| You want banking and savings in one mobile app | SoFi | Integrated checking, savings, and round-ups |
| You run a simple five-goal sinking-fund plan | Either | Both have ample vaults or buckets and scheduled transfers |
| You prioritize the single highest savings rate | Compare current APY | Rates change; neither pays per-bucket interest |
How to choose without overthinking it
Start with goal count and automation style, not the rate. If your sinking-fund system is goal-heavy or you like the idea of an algorithm topping up savings from spare cash, Ally’s larger bucket count and three boosters fit cleanly. If you want your spending, checking, and round-up savings living in one app, SoFi keeps the workflow compact.
Then settle the money questions last. Because both banks apply one APY across the whole balance and both carry FDIC insurance up to the standard limit per depositor, per ownership category, the savings rate becomes a same-day comparison rather than a structural difference. Check the current APY on each issuer’s page, confirm there are no minimum-balance or fee surprises, and pick the workflow you will actually stick with. The best sinking-fund tool is the one whose automation you leave switched on.