Start with Glenside, because it is the cleanest case
Glenside has no council, no mayor and no millage of its own. It is a census-designated place, 7,737 people over 1.27 square miles at the 2020 count, and it sits inside two townships at the same time: Cheltenham and Abington. One ZIP code, 19038, covers both halves.
Here is what that costs, using the county’s own 2026 millage sheet and Abington Township’s tax office, both read 26 August 2026.
| Glenside address | County + MCCC | Municipal | School | Total |
|---|---|---|---|---|
| Cheltenham Township side | 5.952 | 10.8512 | 56.6800 (Cheltenham) | 73.483 |
| Abington Township side | 5.952 | 6.172 | 39.8992 + 1.3738 (Abington) | 53.397 |
Twenty mills apart. On an assessed value of $150,000 that is roughly $3,013 a year, every year, on the same town name. The arithmetic is ours; the millage is the county’s.
None of this is theoretical. Arcadia University has a Glenside mailing address and stands in Cheltenham Township. SEPTA’s Ardsley station carries an address reading Glenside, PA 19038 and stands in Abington Township. Glenside station itself is in Cheltenham. Two school districts run elementary schools inside the same CDP, because the CDP crosses the district line.
Ambler, PA 19002 is mostly not Ambler
Ambler Borough is 0.85 square miles with 6,807 people. The mailing address that carries its name is enormous by comparison, reaching across Upper Dublin, Whitpain, Lower Gwynedd and Horsham townships, and touching Montgomery, Upper Gwynedd and Whitemarsh besides. A geospatial pass against the 2020 Census boundaries put something near four percent of the 19002 area inside the borough itself. That figure is area-based, which makes it a fair picture of the geography and a poor count of households.
Five answers to one address, from the county’s 2026 sheet:
| Where the parcel actually sits | School district | Total mills |
|---|---|---|
| Lower Gwynedd Township | Wissahickon | 33.775 |
| Whitpain Township | Wissahickon | 36.502 |
| Ambler Borough | Wissahickon | 42.367 |
| Horsham Township | Hatboro-Horsham | 44.837 |
| Upper Dublin Township | Upper Dublin | 54.4758 |
Wissahickon School District publishes a district-average assessment of $211,265. Run that assessment through each of those rates and the borough comes out near $8,951 a year while the Upper Dublin side comes out near $11,509 — a gap of about $2,558 a year on one post office. Same county, same 1996 assessment base, same Common Level Ratio. The school district does most of that work: Wissahickon levies 26.6 mills and Upper Dublin levies 41.1418.
Willow Grove is two townships and two school districts
Willow Grove is another census-designated place with no government of its own — 13,730 people across 3.6 square miles, ZIP 19090. It lies in Abington Township and Upper Moreland Township, and the line between them runs roughly along PA 63, which is called Moreland Road where it does that job.
An Upper Moreland parcel pays 7.521 municipal mills and 41.200 to Upper Moreland School District, 54.673 all in. An Abington parcel pays 6.172 and 39.8992 plus the 1.3738-mill referendum levy, 53.397 all in. The address reads Willow Grove either way, and nobody sees which one they bought until the first bill arrives.
One more thing that trips people up: the former naval air station everybody calls Willow Grove is in Horsham Township.
Abington’s seventeen names
Abington is a First Class Township, 58,502 people over 15.52 square miles, the second most populous municipality in the county, governed by commissioners elected one to a ward across fifteen wards. Seventeen unofficial communities inside it carry the mailing names people actually use — Glenside, Roslyn, Willow Grove, Crestmont, Ardsley, Elkins Park, Huntingdon Valley, Meadowbrook and Noble among them.
Every one of those addresses pays Abington Township and Abington School District. Meanwhile Jenkintown Borough, which was carved out of Abington Township in December 1874 and is surrounded by it on three sides, runs its own school district and totals 71.726 mills. Two neighbours, eighteen mills apart, and the mail looks identical.
The same trick, elsewhere in the county
- Blue Bell is a place inside Whitpain Township. The township sets the rate.
- Plymouth Meeting straddles Plymouth Township at 3.8 municipal mills and Whitemarsh Township at 2.3633. Both are Colonial School District, so here the split moves the municipal half of the bill and leaves the school half alone.
- Harleysville is a census-designated place, mostly in Lower Salford Township and partly in Franconia Township — 3.509 municipal mills against 2.480, different sewer authorities, same mailbox.
- Narberth is its own borough, half a square mile, completely surrounded by Lower Merion Township, and its residents are in Lower Merion School District all the same.
- Telford Borough straddles the Bucks and Montgomery line down Main Street. A Bucks-side parcel is assessed by Bucks County on a different base year and pays Bucks County millage, 29.65 for 2026, against Montgomery’s 5.952.
- Roughly half of Horsham Township’s land area carries a Horsham 19044 address at all. A large share of the rest writes Ambler.
How to find out for certain
The envelope is the worst source in the county and the deed is the best one.
Three places carry the real answer. The county parcel record lists the municipality and the school district against the parcel identification number. The deed, and the title commitment drawn from it, describe the land by the municipality it lies in. And the tax bills themselves arrive separately — county and community college together, the municipality on its own, the school district on its own, usually in July.
So when a listing says Glenside or Ambler or Willow Grove, ask for the parcel number instead of the town. Then check the county’s 2026 millage table against the municipality that number belongs to. Montgomery County’s Board of Assessment Appeals sits at One Montgomery Plaza, Suite 301, 425 Swede Street in Norristown, 610-278-3761, and the Recorder of Deeds is at 610-278-3289. Both will tell you which municipality a parcel is in, and neither will care what the post office thinks.
Nothing here is a judgement about any town or any school. It is a boundary question with a public answer, and it is worth twenty mills.
What to do next
Get the parcel number before you get attached to the house, then look up which municipality and which school district it belongs to. When you have that, call and say the street and the township, and one licensed Pennsylvania mortgage lender calls you back — usually the same working day, and by the end of the next working day at the outside. If typing is easier than talking, put the address and the township in the form and send it along. A quarter mile in this county is worth a phone call.