Coming soon

Northumberland County Property Tax Appeal — Deadline and How to File

a house on a hill covered in snow
Photo by Nellie Adamyan on Unsplash

The deadline

Filing deadline

September 1

per the Northumberland County Board of Assessment Revision's Real Estate Assessment Appeal Form, checked 2026-09-11 — source

Northumberland County is reassessing every property for the 2028 tax year. Its Assessment Bureau mails final notices of the new assessments in summer 2027, and an appeal of a notice like that must be received within 40 days of the date of the notice.

Who hears it, and where it goes

Your appeal is decided by the Northumberland County Board of Assessment Revision.

Where to file

Northumberland County Assessment Bureau
3rd Floor, 399 Stadium Drive
Sunbury, PA 17801

The form: Real Estate Assessment Appeal Form.

Filed in person or by mail.

A filing fee is due with the appeal.

An appeal postmarked after the deadline is held over to the next eligible year.

per the Northumberland County Assessment Bureau's Assessment Forms page, checked 2026-09-11 — source

Nearby counties

More: the county index and the Pennsylvania guide.

What your assessed value means here

Pennsylvania — assessed at a base-year value; the STEB Common Level Ratio for your county is about 9.5% of current market. Confirm the ratio on your notice (53 Pa.C.S. §8854).

Northumberland County's common level ratio is drawn from the 2025 CLR (2024 sales data; effective 7/1/2026–6/30/2027) table — the same figure the app uses to compare your assessment to current market value.

Can the board raise your assessment?

Yes. The Northumberland County Board of Assessment Revision can raise your assessment on your own appeal, not only lower it. That is the risk you take by filing, and it is why the case has to be worth making before you file it.

What a board actually weighs

The Northumberland County Board of Assessment Revision decides what your property was worth on the valuation date, so recent comparable sales carry the case, not the size of the bill. The Pennsylvania guide covers the evidence.

Common questions

When is the deadline to appeal my property assessment in Northumberland County?
The deadline is September 1 — per the Northumberland County Board of Assessment Revision's Real Estate Assessment Appeal Form, checked 2026-09-11. Northumberland County is reassessing every property for the 2028 tax year. Its Assessment Bureau mails final notices of the new assessments in summer 2027, and an appeal of a notice like that must be received within 40 days of the date of the notice.
Who decides my appeal in Northumberland County?
The Northumberland County Board of Assessment Revision.
Where do I send my appeal in Northumberland County?
To the Northumberland County Assessment Bureau, 3rd Floor, 399 Stadium Drive, Sunbury, PA 17801 — per the Northumberland County Assessment Bureau's Assessment Forms page, checked 2026-09-11. The form is the Real Estate Assessment Appeal Form.

Sources

Property tax rules and deadlines vary by jurisdiction and can change — verify with your county before relying on this.

PROppeal is coming soon for Northumberland County

When it launches, PROppeal will check your case against real, recent comparable sales and give you an honest verdict — then build the board-ready letter to file — $29.99, no percentage of your savings.

Want a heads-up when it’s live? Email [email protected].