If you keep money in a Philippine savings account, GSave, or a digital bank like Maya, CIMB, or GoTyme, the interest you earn isn't just a flat percentage tacked on once a year — it compounds, meaning you start earning interest on your interest. Understanding exactly how that math works can help you compare which bank actually pays you more, and shows why leaving money untouched for years grows faster than most people expect. This guide walks through the formula, a real peso example using 2026 Philippine bank rates, and how to avoid common math mistakes when estimating your own returns.
To compute compound interest, multiply your deposit by (1 + interest rate divided by compounding periods) raised to the power of total compounding periods, then subtract your original deposit — most Philippine digital banks compound daily, so a ₱50,000 balance at a 3% annual rate grows by roughly ₱1,522 in the first year alone.
- Compound interest formula: A = P(1 + r/n)^(nt), where P is your starting deposit, r is annual rate, n is compounding frequency, t is years
- Digital banks like GoTyme and Maya credit interest daily, meaning your money compounds faster than a traditional bank's monthly or quarterly crediting
- Maya Bank's base savings rate is 3% p.a. as of April 2026, while GoTyme's GoSave pays a flat 3% p.a. with no maintaining balance
- A ₱50,000 deposit at 3% p.a. compounded daily grows to about ₱51,522 after one year versus ₱51,500 under simple interest — the compounding gain is small at low rates but widens significantly over 5-10 years
- BSP's Monetary Board sets the policy rate that indirectly influences how competitive digital banks make their savings rates, so your effective yield can change as BSP adjusts rates
Step 1: Understand the Compound Interest Formula
The standard compound interest formula is A = P(1 + r/n)^(nt), where A is the total amount after interest, P is your principal (starting deposit), r is the annual interest rate written as a decimal (so 3% becomes 0.03), n is how many times per year the interest compounds, and t is the number of years you leave the money untouched.
The key variable most savers overlook is n, the compounding frequency. A bank that compounds annually (n=1) grows your money slower than one that compounds monthly (n=12) or daily (n=365), even if both quote the same headline annual rate, because compounding more often means each small batch of interest starts earning its own interest sooner.
Step 2: Identify Your Bank's Actual Compounding Frequency
Philippine digital banks differ in how often they credit interest. GoTyme's GoSave credits interest daily with no maintaining balance requirement, while Maya Bank pays a 3% per annum base rate (lowered from 3.5% effective April 1, 2026) and is also known for daily interest accrual. CIMB's UpSave pays a 2.5% p.a. base rate, with its GSave product accessible through the GCash app offering promotional rates up to 5% p.a. under certain conditions.
Traditional universal and commercial banks in the Philippines, by contrast, often compound quarterly or even just once a year on regular passbook savings accounts, and their advertised rates are usually far below 1% p.a. — this is exactly why digital banks have become popular for parking emergency funds. Always check the specific product's disclosure statement or in-app rate details, since the same bank can offer different compounding terms for different account tiers.
Step 3: Work Through a Real Peso Example
Suppose you deposit ₱50,000 into a digital savings account paying 3% p.a., compounded daily (n=365). Using the formula A = 50,000 × (1 + 0.03/365)^(365×1), the balance after one full year comes out to approximately ₱51,522 — a gain of about ₱1,522, compared to exactly ₱1,500 if the same rate were applied as simple interest without compounding.
The difference between daily compounding and simple interest looks small in year one, but it widens the longer you leave the money untouched. Over 5 years with no withdrawals, that same ₱50,000 at 3% p.a. compounded daily grows to roughly ₱58,090, versus ₱57,500 under simple interest — a gap of nearly ₱600 that exists purely because of how often the interest compounds.
Step 4: Compare Rates Across Philippine Digital Banks (2026)
As of mid-2026, published base savings rates among major Philippine digital banks include Maya Bank at 3% p.a. (base tier), GoTyme's GoSave at a flat 3% p.a. with no cap or spending requirement, CIMB's UpSave at 2.5% p.a. base (with its GROW product reaching up to 7% p.a. for savers who grow their average daily balance), and BanKo's Todo Savings at around 5% p.a. for balances between ₱5,000 and ₱1,000,000.
Some of these headline rates, such as Maya's promotional tiers reaching into the double digits, require completing monthly in-app tasks or maintaining balance caps to qualify, so always read the fine print rather than assuming the highest advertised number applies to your full balance. Rates also move with Bangko Sentral ng Pilipinas (BSP) policy — when the BSP's Monetary Board raises its benchmark Target Reverse Repurchase Rate, banks typically compete harder for deposits by raising savings rates, and the reverse happens when the policy rate is cut.
Step 5: Use the Rule of 72 for a Quick Mental Estimate
If you want a fast way to estimate how long your money takes to double without doing the full exponential formula, divide 72 by your annual interest rate. At a 3% p.a. rate, 72 ÷ 3 = 24, meaning your deposit would take roughly 24 years to double if left untouched and the rate stayed constant. At a higher promotional rate of 6% p.a., that drops to 72 ÷ 6 = 12 years.
The Rule of 72 is an approximation, not an exact figure — it gets slightly less accurate at very high or very low rates — but it's useful for quickly comparing offers without opening a calculator app.
Step 6: Factor in the 20% Final Withholding Tax
Interest earned on Philippine savings and time deposit accounts is subject to a 20% final withholding tax under the National Internal Revenue Code, which your bank deducts automatically before crediting interest to your account — you never need to file this separately. This means the effective rate you actually receive is your bank's quoted rate multiplied by 0.80. A quoted 3% p.a. rate becomes an effective 2.4% p.a. after tax, so recalculate your compound interest example using the after-tax rate if you want your projection to match what actually lands in your account.
An exception exists for certain long-term peso deposits held for five years or more (commonly structured as long-term negotiable certificates of deposit or similar instruments), which can be tax-exempt under BSP and BIR rules — but this generally does not apply to regular savings or digital bank accounts, only specific long-term deposit products.
Step 7: Avoid the Most Common Calculation Mistake
The most common mistake Filipino savers make is treating the advertised annual rate as if it compounds only once a year, then being confused when their actual year-end balance differs from a quick mental calculation. Remember that n in the formula must match your bank's actual crediting frequency — daily compounding uses n=365, monthly uses n=12, and quarterly uses n=4 — plugging in the wrong n will overstate or understate your real return.
A second common mistake is forgetting to apply the 20% final withholding tax from Step 6 before comparing your projection to your actual bank statement, which makes the compound interest formula look inaccurate when it's actually just missing that deduction.
Step 8: Build a Simple Compounding Table for Multi-Year Planning
For longer-term goals like a 5-year emergency fund target, it helps to build a year-by-year table rather than jumping straight to a 5-year formula. Starting with ₱50,000 at an effective after-tax rate of 2.4% p.a. (3% gross minus 20% withholding tax) compounded daily: Year 1 ends around ₱51,215, Year 2 around ₱52,459, Year 3 around ₱53,733, Year 4 around ₱55,038, and Year 5 around ₱56,374 — each year's ending balance becomes the next year's starting principal.
This step-by-step approach also makes it easier to see the impact of adding regular monthly deposits on top of compounding, since most Filipino savers aren't leaving a single lump sum untouched but are contributing periodically — a scenario the basic compound interest formula doesn't cover on its own and requires a separate annuity-style calculation.
Frequently Asked Questions
Simple interest is calculated only on your original principal amount every period, so a ₱50,000 deposit at 3% p.a. earns exactly ₱1,500 every year with no growth in the base amount. Compound interest instead adds each period's interest back into the principal before calculating the next period's interest, so your base amount grows slightly larger each time interest is credited — this is why a 3% compounded daily account actually earns more than ₱1,500 in the first year, and the gap widens every year after that as more interest gets added to the compounding base.
Not necessarily — a 3% p.a. rate compounded daily can outperform a 3.1% p.a. rate compounded only annually over a full year, because daily compounding lets interest start earning its own interest almost immediately instead of waiting a full 12 months. When comparing two savings products, check both the advertised annual rate and the compounding frequency listed in the bank's terms, since banks aren't required to standardize how often they compound, and a headline rate alone doesn't tell the whole story.
Most major Philippine digital banks compound interest daily, which is one of their key advantages over traditional passbook savings accounts that often compound only quarterly or annually. GoTyme's GoSave credits interest daily with no maintaining balance requirement, and Maya Bank similarly accrues interest daily on its base 3% p.a. rate as of April 2026. Always confirm the current rate and compounding terms in the app before depositing, since digital banks periodically adjust rates in response to BSP policy changes.
Yes — interest earned on regular Philippine savings and time deposit accounts is subject to a 20% final withholding tax under the National Internal Revenue Code, which your bank automatically deducts before crediting interest to your account, so you don't need to file or pay this separately. This means your actual take-home yield is 80% of the quoted rate; a 3% p.a. advertised rate becomes an effective 2.4% p.a. after tax, which is the number you should use when estimating your real year-end balance.
Yes, the same A = P(1 + r/n)^(nt) formula applies to Philippine time deposits, though time deposits typically compound less frequently than digital savings accounts — often monthly or at maturity rather than daily — and usually require locking in your funds for a fixed term (30, 60, 90 days, or longer) in exchange for a higher rate than a regular savings account. Withdrawing before the maturity date on a time deposit usually forfeits some or all of the accrued interest, so factor in your liquidity needs before comparing time deposit rates against a flexible digital savings account.
Bangko Sentral ng Pilipinas sets a benchmark policy rate (the Target Reverse Repurchase Rate) that influences how much banks are willing to pay depositors, since banks generally raise savings rates to stay competitive when BSP tightens policy and cut savings rates when BSP eases policy. As of mid-2026, BSP's policy rate has moved between roughly 4.5% and 4.75% following recent Monetary Board meetings, and digital bank savings rates have shifted alongside these adjustments — so the 3% p.a. rates cited in this guide can change and should be reverified in-app before making deposit decisions.
The two levers you actually control are choosing an account with a higher effective (after-tax) rate and more frequent compounding, and leaving the deposit untouched for as long as possible so compounding has more periods to work — withdrawing and redepositing resets the growth curve. Combining a high-rate digital bank account with consistent additional monthly deposits compounds faster than a single lump sum left alone, since each new deposit also starts earning daily interest from the moment it lands, though calculating that scenario precisely requires an annuity formula rather than the basic single-deposit compound interest formula covered in this guide.
Conclusion
Compound interest rewards patience and frequency — the more often your bank credits interest and the longer you leave your deposit untouched, the more your money grows beyond what a simple percentage calculation would suggest. Before choosing where to park your savings, compare not just the headline annual rate advertised by banks like Maya, GoTyme, or CIMB, but also the actual compounding frequency and the after-tax effective yield, since those details determine what you'll really see in your account balance a year from now.
