Property tax appeal
To appeal a property tax assessment you file, yourself and usually for free, with the office that set the value, by its deadline, with evidence that the value is too high, not uniform with similar properties, or based on wrong facts. HeritageDeed's evidence pack puts that evidence in one PDF from official assessment records: the parcel's assessment history, comparable sales, a neighborhood ratio check, the appeal outcomes already on record and the deadline. Cook County, New York City and Philadelphia, $49.
Deadlines now
Proviso until October 27, 2026; Orland until November 6, 2026; Thornton until November 23, 2026; Rich until December 4, 2026; more on the Cook County page
All 38 townshipsTax Commission deadline for tax classes 2, 3 and 4; March 15, 2027 for class 1 homes.
NYC appealsBoard of Revision of Taxes deadline (first Monday of October), for the next tax year.
Philadelphia appealsCook County dates from the Assessor's published calendar (updated 10/22/26); NYC and Philadelphia dates follow the Tax Commission and BRT rules described on each page.
What the evidence pack includes
- Assessment history: every year the assessor publishes for the parcel (Cook: Assessor mailed, certified and Board of Review values; NYC: market, assessed and taxable value by roll; Philadelphia: market, taxable and exempt value)
- The property characteristics on record (building area, year built, rooms, baths, basement, condition): a wrong characteristic is a ground for appeal in all three places
- Appeal outcomes already on record for the parcel: Cook County Assessor and Board of Review decisions, NYC Tax Commission reductions
- Comparable sales from official sales records, closest in size first, with the median price, the median price per square foot and that figure applied to the subject
- A neighborhood assessment-to-sale ratio check (median ratio, COD, PRD) computed from official assessed values and recorded sales, with the method stated
- The filing deadline for the parcel (in Cook County its township's dates from the Assessor's calendar), the official free route, and the cited rules
- Every record dated; anything that could not be retrieved is flagged as not retrieved, never reported as "none on record"
It is not an appraisal and it does not tell you whether to appeal. The Cook County Assessor's own rule of thumb: if the characteristics on the notice are correct and the estimated market value is within 10 percent of what you think the home is worth, an appeal is unlikely to change the assessment enough to significantly affect the bill.
Where it covers
- Cook County, IllinoisFiles with: Cook County Assessor's Office, then the Board of Review.
- New York CityFiles with: NYC Tax Commission.
- Philadelphia, PennsylvaniaFiles with: Board of Revision of Taxes (and OPA First Level Review).
Questions
How do I appeal my property tax assessment?
File with the office that set the value, by its deadline, with evidence that the market value is too high, not uniform with similar properties, or based on wrong characteristics. In Cook County you file with the Assessor online, free, while your township is open, then with the Board of Review; in New York City with the Tax Commission by March 1, 2027 (tax classes 2 to 4) or March 15, 2027 (class 1); in Philadelphia with the Board of Revision of Taxes by October 4, 2027.
Do I need a lawyer or a tax appeal company?
No. The Cook County Assessor says filing is free and you do not need to hire anyone; the NYC Tax Commission and the Philadelphia Board of Revision of Taxes take applications directly from owners. HeritageDeed does not file appeals or represent anyone: the evidence pack is the public data, organized, for you to use.
Which Cook County townships are open for appeals now?
On the Assessor's calendar today: Proviso, Orland, Thornton, Rich, Lake, Palatine, Jefferson, Schaumburg, North Chicago, Niles, Hanover. Each township's last file date is on the Cook County page.
Where can I see my property tax history?
The evidence pack lists every assessment year the assessor publishes for the parcel. For recorded deeds, sale prices and mortgages, the free property history lookup covers New York City, Philadelphia and Cook County.
What is a good comparable sale?
A recent open-market sale of a similar property nearby: same class or type, similar building area, age and condition. The pack picks sales from official records within 30% of the subject's building area, closest first, and leaves out the sales the assessor itself flags as non-market (multi-parcel, under $10,000, non-sale deeds). It does not adjust for condition or location within the area: choose the ones that truly compare.
What do the ratio statistics mean?
The median ratio is the assessor's market value divided by the sale price for the middle sale; COD measures how evenly homes are valued (lower is more uniform); PRD above 1 means lower-priced homes are valued at a higher share of their price. They are computed by HeritageDeed from official assessed values and recorded sales, not the office's official ratio study.
Does it cover Texas or other states?
Not now. The pack covers Cook County IL, New York City and Philadelphia, where assessments, characteristics and sales are published. Texas is not offered: Texas licenses property tax consultants (Occupations Code chapter 1152).
Related, free: property history lookup (deeds, sale prices and mortgages recorded against an address), recently sold homes in NYC, Cook County and Philadelphia, and the zoning lookup. Buying? A title report is $49 per report.