Mortgage escrow monthly reserve calculator
Add up the yearly property tax and homeowners insurance and spread them over 12 months: 3,600 in tax plus 1,200 in insurance means an escrow reserve of 400 a month, 300 for tax and 100 for insurance. Free in your browser.
- Free
- Runs in your browser
- No sign-up
- Your data stays on your device
Run — free
Worked example
- Annual property tax
- 3,600
- Annual insurance
- 1,200
- Annual escrow total
- 4,800
- Monthly reserve
- 400
- Monthly tax portion
- 300
- Monthly insurance portion
- 100
Mortgage lenders often collect property tax and homeowners insurance through an escrow or impound account so annual bills are paid on time without a surprise lump sum for the borrower. The core math is simple but easy to get wrong when worksheets mix monthly and annual figures or when one premium is still a quote. This mortgage escrow monthly reserve calculator takes the annual property tax amount and the annual insurance premium, divides their sum by twelve, and returns the required monthly escrow reserve contribution together with the annual total and each monthly portion. Negative annual amounts are rejected with a clear invalid input error because a tax or premium cannot be less than zero for reserve planning. Zero is allowed when a component is not escrowed or not yet known.
What monthly escrow reserve means for tax and insurance
An escrow or impound account is a holding account the mortgage servicer uses to accumulate funds for recurring obligations that are not principal and interest. The two largest line items for most residential first mortgages are real property tax and hazard (homeowners) insurance. Instead of the borrower writing one large cheque when the tax bill or insurance renewal arrives, the servicer collects one twelfth of the expected annual cost each month as part of the total housing payment, often called PITI when principal, interest, taxes, and insurance are combined.
The required monthly escrow reserve contribution for those two items is therefore the sum of the annual property tax and the annual insurance premium divided by twelve. Lenders may still require an initial cushion of one or two months of reserves at closing, adjust for known tax increases mid-year, or run a formal annual escrow analysis that can produce a surplus refund or a shortage payment. Those policy layers sit outside this calculator.
Here the job is the deterministic base contribution from the two annual amounts you already know, so worksheets, pre-approval tools, and borrower education pages can show a single transparent monthly figure before the full underwriting package is assembled.
What you can do with it
Purchase and refinance payment estimates
Loan officers and borrowers enter annual tax and insurance to see the monthly escrow reserve before locking a rate or comparing lenders.
CRM and underwriting macros
Broker and credit-union tools convert stored annual tax and HOI quotes into a deterministic monthly reserve for pipeline notes and pre-approvals.
FAQ
What if annual property tax or insurance is negative?
Annual escrow amounts cannot be negative; validation failures are not billed.
Can one of the annual amounts be zero?
Yes. Zero is allowed when that component is not escrowed or not yet known. The monthly reserve then reflects only the non-zero side.
Does this include PMI, flood insurance, or escrow cushions?
No. This calculator covers annual property tax plus annual homeowners (hazard) insurance only. Add other annual premiums yourself if needed; initial cushions and shortage adjustments are lender policy outside this formula.
How do I calculate my monthly escrow payment?
Add the annual property tax and the annual homeowners insurance premium, then divide by 12. With 3,600 in tax and 1,200 in insurance, the annual total is 4,800 and the monthly reserve is 400.
Why can my lender's escrow amount differ from this result?
Lenders may ask for a cushion of one or two months at closing, adjust for known tax increases or run an annual escrow analysis that ends in a refund or a shortage payment. Here you get the base monthly contribution only.
Related tools
For developers — API access
Everything on this page is available programmatically. This section is for teams who want to wire it into their own systems; everyone else can just use the tool above.
API endpoint
Prefer to automate it? One authenticated POST creates the task; the result comes back by webhook or a signed link. The same capability also runs here on the web, by email and from Telegram — and soon from our app too.
Call it from your stack
curl -X POST https://api.kit.forhosting.com/realestate/escrow-monthly-reserve-calc \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"annual_property_tax":3600,"annual_insurance":1200}'const res = await fetch("https://api.kit.forhosting.com/realestate/escrow-monthly-reserve-calc", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"annual_property_tax": 3600,
"annual_insurance": 1200
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/realestate/escrow-monthly-reserve-calc",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"annual_property_tax": 3600,
"annual_insurance": 1200
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/realestate/escrow-monthly-reserve-calc", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"annual_property_tax":3600,"annual_insurance":1200}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"annual_property_tax":3600,"annual_insurance":1200}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/realestate/escrow-monthly-reserve-calc", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"annual_property_tax": 3600,
"annual_insurance": 1200
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "realestate.escrow_monthly_reserve_calc",
"status": "queued",
"_links": {
"result": "/tasks/tsk_…/result"
}
}The API is asynchronous: the call returns a task_id immediately and the result arrives by webhook. Polling is capped at 1 req/s per task.
Pricing
Published price — no tokens, no invented credits. A failed task is never charged.
Errors
| HTTP | Code | Meaning |
|---|---|---|
401 | unauthorized | Missing or invalid API key. |
402 | insufficient_balance | Your balance doesn't cover the task price. |
404 | unknown_type | That task type doesn't exist. |
429 | rate_limited | Too many requests. Use the webhook instead of polling. |
Technical notes
What monthly escrow reserve means for tax and insurance
That identity is the contract of this capability: monthly_reserve equals annual_property_tax plus annual_insurance, all over twelve.
Input contract, response shape, and error behaviour
Each must be a finite number greater than or equal to zero, or a numeric string that parses to such a number. Zero is valid for either side when that cost is not part of the escrowed set or when you want only the other component’s monthly share. Example: annual property tax of three thousand six hundred and annual insurance of one thousand two hundred yield an annual escrow total of four thousand eight hundred and a monthly reserve of four hundred in the same currency unit you used for the inputs. The calculator does not convert currencies, estimate future tax reassessments, or model PMI or flood insurance as separate products—add those annual premiums into insurance or extend your own pipeline if you need a broader escrow stack. POST a JSON body with two required fields: annual_property_tax and annual_insurance. Aliases property_tax, annual_tax, tax_annual, and taxes map to the tax field; insurance, annual_hoi, homeowners_insurance, and hazard_insurance map to the insurance field for shorter form labels. Missing fields, empty strings, NaN, and Infinity fail with invalid_input naming the problem. On success the body echoes cleaned annual_property_tax and annual_insurance (half-up to two decimal places), annual_escrow_total as their sum, monthly_reserve as the total divided by twelve, monthly_tax_portion and monthly_insurance_portion as each annual amount over twelve, plus formula and method strings for display and client branching.
Where an escrow monthly reserve API earns its keep
Purchase and refinance workflows need a fast monthly tax-and-insurance reserve so borrowers can compare total payment scenarios without opening a full loan origination system. Classroom and certification courses that teach PITI can use the deterministic oracle to check student worksheets. Mortgage brokers and credit unions embed the same endpoint in CRM macros so staff quote consistent escrow estimates from assessed tax and quoted HOI. Proptech budgeting apps and spreadsheet replacements call the API under KIT balance at $0.002 per successful item when they already store annual tax and insurance and only need the monthly split.
Integration use cases
Buyer education and proptech widgets
Landing pages and mobile apps show a free escrow monthly reserve calculator that matches the API for transparent PITI-style education.
Technical questions
How is the monthly escrow reserve calculated?
monthly_reserve = (annual_property_tax + annual_insurance) / 12. The API also returns the annual total and each monthly tax and insurance portion, rounded half-up to two decimals.
What does the mortgage escrow monthly reserve calculator cost?
The browser tool is free. API requests use prepaid KIT balance at $0.002 per successful call; invalid input is not billed.