Short answers

Does the tool send my income or loan details anywhere?

No. Every calculation runs in your browser, on your own device. Nothing you type is transmitted to a server, written to a database, or retained after you close the tab. The only exception is the share link, which encodes your inputs into the URL itself and is created only when you press the copy button.

Why is my payment going to jump, and when?

Because the advertised rate is promotional and lasts a fixed number of months, after which the loan floats at a base rate plus a margin. On a typical Vietnamese home loan the instalment rises by around 37% in the first month after the promotion ends. If a principal grace period ends at the same time, the rise can exceed 140%.

Worked through in the thirteenth month.

What is an effective interest rate, and why does it differ from the rate on my offer?

It is the single fixed rate that, with no fees at all, would produce exactly the payments you are actually making. It folds the promotional period, the floating period, upfront fees and any early settlement cost into one number. A loan advertised at 6.9% can have an effective rate above 11%, and above 12.6% once insurance taken at drawdown is counted.

The method is on the methodology page and explained in one number.

What is the base rate, and can the bank change it whenever it likes?

The base rate is a reference rate the bank publishes and resets at intervals set in your contract, commonly every three or six months. The margin added on top is fixed for the term. Most contracts contain no cap on how far the base rate can move, so the only part of the floating rate the bank has committed to is the margin.

What does the early repayment fee apply to: the original loan or the balance?

Almost always the amount you repay early, not the original loan. On a 2.4 billion dong loan settled in month 24, the balance is 2.16 billion and a year-two tier of 2% produces a fee of 43,200,000 dong. Check whether your contract also treats monthly overpayments as early repayment, because many do.

What is promotional interest clawback?

A clause requiring you to repay the interest the bank discounted during the promotional period if you settle inside a stated window, commonly 24 to 60 months from drawdown. It is charged on top of the early repayment fee and is frequently larger. On the worked example it is 107,870,000 dong against a penalty of 43,200,000.

Is the insurance the bank is offering compulsory?

Property insurance is usually a genuine condition, because the bank holds the property as security. Credit life cover on the borrower is usually not a condition of the loan itself, but it may be a condition of the promotional rate you were quoted. The question to ask is what the rate is with the insurance and what it is without, both in writing.

Should I choose equal principal or equal instalments?

Equal principal costs substantially less over the term, roughly 932 million dong less on the worked example, because the balance falls faster. Equal instalments give a lower and more predictable payment, which matters if the post-promotional instalment would stretch your budget. Choose equal principal if you can absorb the month thirteen payment stress tested two points higher; otherwise choose equal instalments.

How much should the loan payment be as a share of my income?

Banks will often approve at 50 to 60% of gross income, calculated on the promotional payment. A more durable test is the peak required payment at the floating rate under 40% of income, still under 50% when stress tested two percentage points higher, with a positive surplus after living costs and six months of the peak payment held in cash.

Is it worth refinancing to another bank?

It depends almost entirely on whether your clawback window has closed. On the worked example, leaving in month 36 costs 138,470,000 dong while leaving in month 37 costs 20,300,000. As a rule, refinancing pays only when the total cost of leaving and arriving is less than the saving over the new promotional period alone.

Does the tool tell me which bank to borrow from?

No. There are no bank rankings, no affiliate links and no referral commissions anywhere on this site. You enter the terms of an offer and the tool prices it. Comparing two offers means running both and comparing the effective rates.

How is this site funded?

By advertising served through Google Ad Manager. Advertising is clearly labelled and kept separate from the analysis, no advertiser has any influence over what is written, and the tool itself contains no advertising in the results.

Set out in full in the advertising disclosure.

Can I trust the numbers?

The arithmetic is open. Every formula is published on the methodology page, the engine is covered by forty-three automated tests checked against hand calculations, and the source code is MIT licensed. If you find a figure you believe is wrong, the contact page asks for the share link and the figure you think is correct, and corrections are made quickly.

Is this financial advice?

No. It is a calculator and a set of general guides. It takes no account of your circumstances, it cannot know the wording of your contract, and it is not a substitute for professional advice. If the loan is large relative to your income, talk to someone qualified before signing.

What does the tool not model?

It does not forecast future interest rates, it does not cover property taxes, management fees, maintenance or movements in property prices, and it does not assess whether you would be approved. It also assumes a single floating rate after the promotion rather than a quarter-by-quarter schedule.

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The tool itself needs none. Advertising cookies and device identifiers are only set if you agree to them in the consent banner, and you can change that decision at any time from the cookie preferences link in the footer.

Detailed in the cookie policy.