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How the tools work

Calculation methodology

Every public calculator should be inspectable. This page records what each tool is for, which inputs it uses, how the estimate is produced, and where an official or provider result can differ.

Rules that apply to every calculator

Public calculator inputs stay in the browser and are not sent to Kasyafi analytics or advertising systems. Kasyafi validates reasonable input ranges, uses integer centavos where practical, labels future rates as assumptions, and keeps regulated calculations tied to a visible source and verification date.

An estimate is only as complete as its inputs. A zero can mean “none,” while an omitted obligation can falsely make a result look safer. Recalculate when a balance, rate, due date, rule, or income assumption changes.

Method 01

Philippine take-home salary

Purpose: Estimate net monthly and per-pay-period salary after statutory employee contributions and withholding tax.
Inputs: Gross monthly basic salary, pay frequency, taxable allowances or additional pay, and optional contribution settings exposed by the calculator.
Formula or approach: Kasyafi estimates SSS, PhilHealth, and Pag-IBIG employee shares using the implemented schedules, determines taxable compensation after applicable statutory deductions, applies the BIR withholding table for the selected pay period, then subtracts deductions from gross compensation.
Rounding: Money is represented in integer centavos. Intermediate statutory results follow the rounding rules implemented for each schedule; displayed totals are formatted to two decimal places.
Simplifications: The public estimate does not reproduce every employer payroll code, de minimis benefit, prior-period adjustment, annualization reconciliation, exemption, or company policy.
Why an actual result may differ: Actual net pay can change with attendance, benefit classification, taxable bonuses, employer cutoffs, prior payroll corrections, contribution treatment, and BIR year-end adjustment.

Source basis: BIR income-tax and withholding guidance
Last verified September 3, 2026

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Method 02

Philippine payslip audit

Purpose: Compare an entered payslip with an independent estimate and show where gross pay, statutory deductions, tax, and net pay differ.
Inputs: Pay period, basic salary, allowances and premiums, hours and day types, displayed deductions, and other taxable or non-taxable amounts.
Formula or approach: The audit rebuilds estimated earnings, statutory contributions, and withholding from the supplied facts, then compares estimated line items and net pay with the values entered from the payslip.
Rounding: Line items are calculated in centavos and variances are shown after centavo rounding. Small employer rounding differences should be interpreted separately from structural differences.
Simplifications: A public form cannot infer company payroll codes, collective agreements, time-bank rules, retroactive changes, or whether every entered allowance qualifies for a tax exclusion.
Why an actual result may differ: Differences can come from payroll cutoffs, attendance records, prior adjustments, benefit classification, employer contribution tables, taxable-year reconciliation, or an incomplete input.

Source basis: DOLE workers’ statutory monetary benefits
Last verified September 3, 2026

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Method 03

BIR withholding tax

Purpose: Estimate compensation withholding for a selected payroll period using the implemented 2023-onward tax table.
Inputs: Taxable compensation for the period and payroll frequency.
Formula or approach: The calculator chooses the matching BIR compensation range, applies the bracket’s base tax plus the marginal rate to compensation above the threshold, and reports the estimated withholding.
Rounding: Threshold comparisons use the entered peso value; the result is rounded to the nearest centavo for display.
Simplifications: It treats the entered amount as taxable compensation and does not perform an employer’s complete annual tax reconciliation or classify every benefit.
Why an actual result may differ: Official withholding can differ because of annualization, prior payrolls, irregular compensation, taxable-benefit classification, corrections, exemptions, or a later BIR issuance.

Source basis: BIR Revenue Regulations No. 8-2018 digest
Last verified September 3, 2026

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Method 04

SSS contribution

Purpose: Estimate employee and employer SSS components for a monthly salary credit under the implemented 2025 schedule.
Inputs: Monthly compensation and membership or contribution context offered by the calculator.
Formula or approach: Kasyafi maps compensation to the applicable monthly salary-credit row, then returns the employee and employer shares and any mandatory provident-fund component represented in that row.
Rounding: The official table values are stored and returned in centavos rather than recalculated from a displayed percentage alone.
Simplifications: The estimate assumes the selected member context fits the table and does not resolve delinquency, employer reporting, retroactive coverage, special payment rules, or benefit eligibility.
Why an actual result may differ: Actual records can differ because of the applicable contribution month, membership type, posted compensation, employer correction, or a newer SSS schedule.

Source basis: SSS contribution table
Last verified September 3, 2026

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Method 05

PhilHealth contribution

Purpose: Estimate the monthly premium and employee/employer split using the current implemented rate, floor, and ceiling.
Inputs: Monthly basic salary and the employee-share context shown by the calculator.
Formula or approach: The premium basis is constrained to the applicable salary floor and ceiling, multiplied by the implemented premium rate, and ordinarily divided equally between employee and employer for formal-sector employment.
Rounding: The total premium and shares are rounded to centavos; the split reconciles to the rounded total.
Simplifications: The calculator does not determine membership arrears, direct-contributor classifications, employer reporting errors, or whether a compensation item belongs in basic salary.
Why an actual result may differ: Actual deductions can differ with salary definition, employment category, contribution period, retroactive adjustments, or a later PhilHealth advisory.

Source basis: PhilHealth Advisory 2025-0002
Last verified September 3, 2026

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Method 06

Pag-IBIG regular savings contribution

Purpose: Estimate mandatory employee and employer Pag-IBIG Fund contributions from monthly compensation.
Inputs: Monthly compensation and the contribution settings presented by the calculator.
Formula or approach: Kasyafi applies the implemented employee and employer rates to compensation subject to the implemented maximum fund salary, then shows both shares and the combined contribution.
Rounding: Each share is rounded to centavos and the displayed total is their sum.
Simplifications: The estimate does not resolve employer remittance timing, voluntary top-ups, membership gaps, penalties, or special coverage classifications.
Why an actual result may differ: Actual contributions can differ because of the compensation basis reported by the employer, voluntary savings, membership status, retroactive corrections, or a newer Pag-IBIG circular.

Source basis: Pag-IBIG Fund official website
Last verified September 3, 2026

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Method 07

13th-month pay

Purpose: Estimate statutory 13th-month pay from eligible basic salary earned during the calendar year.
Inputs: Eligible basic salary by month or total eligible basic salary, plus the work-period information shown by the calculator.
Formula or approach: The core estimate is total eligible basic salary earned during the calendar year divided by 12. The calculator separates the gross estimate from any tax treatment that may depend on aggregate benefits.
Rounding: The final quotient is rounded to the nearest centavo.
Simplifications: The tool cannot decide whether a particular allowance, leave, absence, commission, or employment arrangement belongs in the statutory basic-salary base.
Why an actual result may differ: Employer results can differ with actual payroll history, eligible-basic-salary classification, unpaid periods, resignations, company benefits above the statutory minimum, and tax aggregation.

Source basis: Official Gazette — Presidential Decree No. 851
Last verified September 3, 2026

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Method 08

Overtime pay

Purpose: Estimate overtime premium pay for the selected workday or holiday context.
Inputs: Basic salary or hourly rate, ordinary working days or divisor context, overtime hours, and day classification.
Formula or approach: Kasyafi derives or uses the hourly rate, applies the implemented DOLE multiplier for the selected day type, and multiplies it by overtime hours. Night overtime can add the applicable night premium.
Rounding: Hourly and premium amounts are calculated in centavos, with the final overtime amount rounded to centavos.
Simplifications: The estimate assumes the worker and hours are covered by the selected statutory rule and does not determine exemptions, company policies, compressed schedules, or collective agreements.
Why an actual result may differ: Actual pay can differ with the employer’s valid divisor, coverage, rest-day designation, holiday proclamation, payroll cutoff, time records, or a more favorable company rule.

Source basis: DOLE workers’ statutory monetary benefits
Last verified September 3, 2026

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Method 09

Night differential

Purpose: Estimate the statutory premium for covered hours worked inside the night-work window.
Inputs: Base hourly or salary information, shift start and end, break duration, day classification, and whether hours are overtime.
Formula or approach: The tool identifies working time within 10 p.m. to 6 a.m., adjusts entered break time proportionally, applies the day-type base multiplier, and calculates a 10% night premium on that effective base.
Rounding: Night-window hours are displayed to two decimal places and pay is rounded to centavos.
Simplifications: Proportional break allocation is an estimate when the actual break timing is unknown. Coverage, exclusions, and more favorable employer rates are not inferred.
Why an actual result may differ: Actual pay can differ with exact clock records, break timing, employment coverage, a company’s higher premium, payroll rounding, or the correct day classification.

Source basis: DOLE explanation of employee compensation
Last verified September 3, 2026

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Method 10

Holiday pay

Purpose: Estimate pay for an unworked or worked regular, special, double, or rest-day holiday scenario.
Inputs: Daily or derived daily rate, holiday/day classification, hours worked, and overtime or night hours when applicable.
Formula or approach: Kasyafi applies the implemented first-eight-hour multiplier, then separately applies overtime and night premiums according to the selected scenario.
Rounding: Each component is rounded to centavos and the total is the sum of the displayed components.
Simplifications: The calculator cannot determine holiday-pay eligibility, absence rules, local proclamations, company policies, or whether the chosen day classification is correct.
Why an actual result may differ: Actual pay can differ with worker coverage, prior-day attendance rules, rest-day scheduling, official proclamations, payroll divisor, collective agreements, and more favorable benefits.

Source basis: DOLE holiday-pay advisories
Last verified September 3, 2026

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Method 11

Pag-IBIG MP2 projection

Purpose: Illustrate how an initial amount and regular contributions could accumulate over the five-year MP2 term under an assumed dividend rate.
Inputs: Starting savings, recurring contribution, contribution frequency, term timing, and an annual dividend-rate assumption.
Formula or approach: The projection adds contributions on the selected schedule and applies the declared annual assumption across the modeled balance. It reports contributions separately from estimated dividends.
Rounding: Contributions and period dividends are rounded to centavos; the schedule reconciles to the displayed projected balance.
Simplifications: The rate is an assumption, not a promised future dividend. The model may not match Pag-IBIG’s exact declaration timing, account posting dates, tax treatment, membership status, or payout election.
Why an actual result may differ: Actual results depend on contribution posting dates, declared annual dividends, eligibility, account rules, interrupted payments, and whether dividends are compounded or paid annually.

Source basis: Pag-IBIG Fund official website
Last verified September 3, 2026

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Method 12

Safe-to-Spend

Purpose: Estimate the flexible amount left before the next payday after protecting entered obligations and a chosen buffer.
Inputs: Available cash, confirmed income before payday, bills, debt payments, essential living costs, savings target, and safety buffer.
Formula or approach: Available cash + confirmed incoming cash − bills − debt payments − essentials − savings target − safety buffer. A negative result is shown as a projected shortfall.
Rounding: Every input is converted to integer centavos before addition or subtraction.
Simplifications: The tool uses the totals supplied and does not predict an omitted bill, uncertain income, transaction timing, account hold, or emergency expense.
Why an actual result may differ: The result changes whenever an obligation, income date, available balance, savings decision, or buffer changes. It is not a bank balance or spending authorization.

Source basis: Kasyafi calculation methodology and source code
Last verified September 3, 2026

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Method 13

Debt payoff comparison

Purpose: Compare minimum-only, snowball, and avalanche repayment paths for up to ten debts.
Inputs: Balance, APR, minimum payment, total monthly debt budget, optional additional payment, and calculation date.
Formula or approach: The simulation accrues simplified monthly interest, pays every listed minimum, directs the extra amount by smallest balance for snowball or highest APR for avalanche, and rolls released payments forward after payoff.
Rounding: Balances, interest, and payments are simulated in integer centavos; monthly interest is rounded to the nearest centavo.
Simplifications: Rates and payments are held constant. New charges, fees, daily-balance interest, promotional-rate expiry, delinquency, and lender-specific allocation are excluded.
Why an actual result may differ: Statement outcomes can differ with daily balances, posting dates, changing minimums, rate changes, fees, payment allocation, and new transactions.

Source basis: BSP financial-education resources
Last verified September 3, 2026

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Method 14

Credit-card interest

Purpose: Compare payoff time and estimated interest for a fixed monthly payment with and without an extra amount.
Inputs: Outstanding balance, APR or monthly rate, monthly payment, optional extra payment, and calculation date.
Formula or approach: The model applies APR ÷ 12 or the entered monthly rate to the opening monthly balance, adds rounded interest, subtracts the fixed payment, and repeats for up to 1,200 months.
Rounding: Interest and payments are handled in centavos and rounded each simulated month.
Simplifications: It is a monthly fixed-rate model, not an average-daily-balance statement engine. It excludes new purchases, grace periods, cash advances, fees, promotions, and changing minimums.
Why an actual result may differ: Issuer results can differ because of daily posting, compounding, payment allocation, transaction type, residual interest, changing rates, fees, and taxes.

Source basis: BSP Circular No. 1165
Last verified September 3, 2026

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Method 15

Loan amortization

Purpose: Estimate a fixed-rate monthly installment, total interest, payoff date, and amortization schedule.
Inputs: Principal, annual nominal rate, term in months, optional recurring extra payment, and start date.
Formula or approach: For a positive rate, Kasyafi uses the standard level-payment amortization formula with monthly rate r = annual rate ÷ 12. Each month adds rounded interest to the remaining balance and applies the scheduled plus extra payment; zero-rate loans divide principal across the term.
Rounding: The scheduled payment is rounded to centavos. Monthly interest is rounded to centavos, and the last scheduled installment reconciles any small residual balance.
Simplifications: The model assumes a fixed nominal rate and monthly schedule. It excludes fees, insurance, taxes, variable rates, balloon payments, skipped dates, and lender day-count conventions.
Why an actual result may differ: A lender disclosure can differ because of effective interest, add-on pricing, fees, payment timing, grace periods, repricing, and prepayment terms.

Source basis: BSP loan calculator and consumer resources
Last verified September 3, 2026

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Method 16

Budget ratios

Purpose: Show whether entered monthly take-home income covers the chosen allocations and what share each category uses.
Inputs: Monthly take-home income and amounts for housing, utilities, groceries, transport, debt, insurance, education, subscriptions, other fixed costs, savings, and flexible spending.
Formula or approach: The calculator sums allocations, subtracts them from income for the remaining buffer, and divides each category by income to show its percentage. Committed expenses exclude the separately entered savings target and flexible amount.
Rounding: Amounts are converted to centavos. Ratios are rounded to one decimal place.
Simplifications: No generic percentage is treated as a requirement. The calculator does not judge whether a category is necessary or predict irregular costs omitted from the inputs.
Why an actual result may differ: Actual cash flow differs when income timing, variable spending, annual expenses, taxes, or transfers are not represented by the monthly totals.

Source basis: BSP financial-education resources
Last verified September 3, 2026

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Method 17

Emergency-fund coverage

Purpose: Translate a target number of months into a peso reserve and estimate the time needed to close the gap.
Inputs: Monthly essential expenses, current emergency savings, target months, regular monthly contribution, and optional one-time contribution.
Formula or approach: Target = essential monthly expenses × target months. Gap = maximum of zero and target minus current savings and any one-time amount. Months to target = gap divided by the regular contribution, rounded up.
Rounding: Peso inputs are converted to centavos; the funding timeline rounds up to a whole contribution month.
Simplifications: The model does not add savings interest, inflation, withdrawals, changing expenses, job-risk probability, insurance coverage, or asset-sale timing.
Why an actual result may differ: A suitable target is personal and can change with dependents, income stability, health, insurance, access to support, and the liquidity of existing savings.

Source basis: BSP PiTaKa financial-education manual
Last verified September 3, 2026

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Method 18

Invest or pay debt

Purpose: Compare debt reduction, investing, and split paths while checking liquidity and emergency protection first.
Inputs: Available extra cash, essential expenses, emergency savings and target, debt balances/rates/minimums/fees, investment return assumption, risk, liquidity, lockup, fees, and horizon.
Formula or approach: The decision engine first checks required minimums and emergency coverage. It then compares modeled debt interest avoided with risk-adjusted investment growth, fees, lockups, liquidity, promotional rates, and secured-debt context across available scenarios.
Rounding: Money is modeled in centavos and rates in basis points. Displayed percentages and scenario totals are rounded for readability.
Simplifications: Investment returns and future debt costs are assumptions. The model does not forecast markets, taxes, credit-score effects, lender behavior, or every consequence of early repayment.
Why an actual result may differ: The preferable action can change with risk capacity, cash needs, job stability, taxes, fees, guarantees, product terms, prepayment rules, and actual future returns.

Source basis: BSP financial-education resources
Last verified September 3, 2026

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Last verified September 3, 2026. Regulated inputs are checked against the linked primary sources; non-regulated tools are checked against their implemented formulas and tests.