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Tax Proration Calculator

Property tax is the biggest prorated item at closing. Each party pays for the days they owned the property. Rules vary by state — arrears-billing states like Illinois and Pennsylvania differ dramatically from prepaid states.

Annual property tax

Billing cycle

Day of month at close

Month at close (1-12)

Day-count convention

Seller's share

$3,437

days seller owned × per-day rate

Buyer's share

$2,963

Per-day tax

$17.53

Arrears credit to buyer

if paid in arrears

Days in seller's period

196

How the math works

Property tax is prorated so each party pays for the days they owned the property. In prepaid states (tax paid at start of year), the seller gets credit for the unused portion. In arrears states (tax paid at end of year), the buyer gets credit for the seller's portion of the upcoming bill.

States vary: Illinois and Pennsylvania pay in arrears — sellers credit the buyer. California uses fiscal year (July 1). Some jurisdictions use 30/360 day-count banking convention; others use actual days. Title company handles the math — this tool helps you verify.

Editorial noteMaintained by EveryCalc - Reviewed June 2026

EveryCalc calculators are designed for fast, practical estimates with transparent inputs and no required account. We use plain formulas, visible assumptions, and related tools so visitors can check the result from more than one angle.

Results are informational only. For financial, tax, legal, medical, construction, or other high-impact decisions, verify the output against primary sources or a qualified professional.

Learn more about our review process on the EveryCalc methodology page.

How this calculator works

What this page estimates

This Tax Proration Calculator is built to give a quick, browser-based estimate for tax proration. Property tax is the biggest prorated item at closing. Each party pays for the days they owned the property. Rules vary by state — arrears-billing states like Illinois and Pennsylvania differ dramatically from prepaid states. The inputs stay on the page during normal use, and the result should be treated as an estimate for planning, comparison, or education rather than professional advice.

Calculation approach

The calculator applies the standard relationship implied by the inputs, then formats the answer so it can be checked and reused. For finance tools, the most important step is using consistent units, rates, time periods, and assumptions before comparing the result with another calculator or outside quote.

Example workflow

For example, start with a realistic value you already know, change one input at a time, and watch how the answer moves. That makes it easier to tell whether the result is being driven by the main amount, the rate, the time period, or a unit conversion.

Practical checks

Use current, real-world numbers when the result affects money, health, tax, or legal decisions.
Run a low, base, and high case when the inputs are estimates.
Check the related calculators below when the next decision depends on a different assumption.

How to interpret the tax proration result

Best use

Use the result as a planning number for comparing payments, rates, returns, tax reserves, or cash-flow choices before you request a quote or make a commitment.

Cross-check

Compare the answer with the contract, lender estimate, tax form, brokerage statement, payroll record, or invoice that will control the real-world outcome.

Watch for

Do not rely on a single optimistic rate, return, or fee assumption. Money pages work best when you run low, base, and high cases and keep professional advice separate from the estimate.

This page belongs to the Finance calculator library, so the answer should be read in the context of the decision you are modeling rather than as a universal rule.

Before relying on this tax proration estimate

Most calculator mistakes come from the inputs, not the arithmetic. Use this short audit before you reuse the answer in a spreadsheet, quote, application, or important conversation.

Confirm source numbers

Match balances, rates, fees, taxes, income, and payment dates against the lender quote, payroll record, tax form, statement, invoice, or contract.

Separate cash flow from total cost

A lower monthly payment can still cost more over time if fees, interest, taxes, or a longer term are hidden in the structure.

Run conservative cases

Test at least one higher-cost or lower-return case before using the output for a purchase, refinance, investment, loan, or tax decision.

Rerun this page when the rate, price, term, fee, tax rule, income, expense, or expected holding period changes.

How to Use

Enter the annual property tax.
Pick billing cycle: calendar year, fiscal year (CA July), or arrears (IL, PA, OH).
Enter the closing day and month.
Pick day-count convention. Most states use actual days; some use 30/360.

Frequently Asked Questions

Why does billing cycle matter?

If tax is paid at the start of the year (prepaid), the seller's portion is a credit to the seller (they already paid). If it's paid at the end (arrears), the seller's portion is a credit to the buyer (they'll owe it later).

What's the fiscal year in California?

California's property tax fiscal year runs July 1 to June 30. First installment (July-Dec) is due Nov 1, second (Jan-June) due Feb 1. Proration reflects the fiscal year, not calendar year.

What about supplemental tax?

California reassesses at sale, generating a supplemental bill for the difference between old and new assessed values. This is NOT prorated at closing — the buyer pays it for the portion they own.

Which day-count convention should I use?

Most closings use actual days (365). A few use 30/360 (banker's year). Your title company's standard practice determines which; verify by reviewing the Closing Disclosure proration line.