How We Calculate True Cost | Methodology

Core principle

We compute hidden monthly totals by summing individual cost line items and dividing by 12. We never use pre-baked aggregate estimates. If a single cost figure is corrected, the total automatically reflects the change. This is a deliberate choice — most cost-of-living calculators show round-number guesses; we show math you can verify.

Mortgage assumptions

All calculations assume 20% down payment, 7.0% fixed interest rate, 30-year term. These assumptions are displayed in the calculator — they are not hidden inputs. The mortgage figure is derived from the standard amortization formula.

We do not ask you to enter your rate because the purpose of the calculator is to reveal the hidden costs, not to replicate a mortgage origination tool. Adjust the purchase price slider to model different loan scenarios.

Property tax

Property tax is calculated from purchase price × effective tax rate, divided by 12. This approximates the California Prop 13 baseline year — your assessed value begins at purchase price and increases by no more than 2%/year.

Nevada County effective rate: 0.98% of purchase price annually. Placer County (Northstar): 1.12%. Individual parcels vary; verify with the county assessor for specific parcels. Note: property tax is shown in the calculator but is not included in the “hidden cost” total — it appears in both the Zillow column and the true cost column as a shared baseline.

Per-category data sources

Figures verified April 2026. Estimated figures are marked; we're actively seeking verified quotes for all estimate line items.

HOA / Road association

Tahoe Donner

$3,621/yr ($302/mo) — Tahoe Donner Association 2026 assessment, verified April 23, 2026. Covers rec facilities, trails, roads. Zillow has historically misquoted this as $275/mo.

Glenshire

$561/yr ($47/mo) — Glenshire Devonshire Residents Association (GDRA) 2026 assessment, verified. Road maintenance and common areas only.

Truckee Proper

$0/yr — Most SFH in Truckee Proper have no HOA. Verify per address for condos and planned developments.

Northstar

$8,000/yr ($667/mo) — NPOA base fee $1,700/yr + sub-HOA midpoint estimate ~$6,300/yr. Snow removal is typically included in HOA at Northstar.

Heating

Tahoe Donner

$3,000/yr ($250/mo) — Propane estimate (~1,200 gal/yr at market rates). At elevation 6,500 ft, natural gas is not available. Verified quote from Kamps Gas / AmeriGas pending (s3-31a).

Glenshire

$2,200/yr ($183/mo) — Web-sourced estimate. Glenshire's 'banana belt' microclimate results in milder winters; mix of propane and natural gas by street.

Truckee Proper

$1,800/yr ($150/mo) — Liberty Utilities residential natural gas rate estimate, 2024 avg.

Northstar

$2,000/yr ($167/mo) — Liberty Utilities / SoCalGas residential rate estimate. Northstar Village connected to natural gas.

Snow removal

Tahoe Donner

$1,250/yr ($104/mo) — Elements Mountain Company verified quote, April 23, 2026. Full-season contract for a 0.44-acre TD lot (12817 Stockholm Way reference property).

Glenshire

$900/yr ($75/mo) — Web-sourced estimate. Lower snowfall than TD due to lower elevation and banana belt climate. Private road service still required.

Truckee Proper

$800/yr ($67/mo) — Web-sourced estimate for private driveway only. Public streets plowed by Town of Truckee and Caltrans.

Northstar

$0 — Snow removal typically included in HOA — one genuine benefit of the high dues.

Defensible space maintenance

Tahoe Donner

$2,500/yr ($208/mo) — Elements Mountain Company verified quote, April 23, 2026. CAL FIRE Zone 2 — midpoint of $2,000–$3,000 range for annual professional maintenance.

Glenshire

$2,000/yr ($167/mo) — Web-sourced estimate. Nevada County WUI zone; slightly lower intensity than Tahoe Donner.

Truckee Proper

$1,500/yr ($125/mo) — Web-sourced estimate. Town limits and municipal fire proximity reduce WUI exposure. Still required by CAL FIRE regulation.

Northstar

$2,500/yr ($208/mo) — Web-sourced estimate. Placer County WUI designation plus TRPA overlay adds regulatory complexity.

Fire insurance

Tahoe Donner

$6,300/yr ($525/mo) — Scaled from verified FAIR Plan data point: $1.77M home, 4,337 sq ft property in Truckee. No admitted carrier serves this area — FAIR Plan only.

Glenshire

$5,500/yr ($458/mo) — FAIR Plan estimate, scaled from Truckee data point. Proximity to TFD Station 94 provides marginal benefit.

Truckee Proper

$4,500/yr ($375/mo) — Lowest in region. Municipal fire response infrastructure and hydrant access improve FAIR Plan risk classification.

Northstar

$7,000/yr ($583/mo) — Highest in region. Elevation, fuel load, and high property values drive FAIR Plan premiums. Placer County exposure.

Asphalt sealing

Tahoe Donner

$300/yr ($25/mo) — Elements Mountain Company quote: $550–$650 every 2 years, annualized to $300/yr. Private driveways common in TD.

Glenshire

$0 — Road association paves common streets. Individual driveway sealing not typically required.

Truckee Proper

$0 — Town-maintained streets. No individual sealing typically required.

Northstar

$0 — HOA maintains private roads. No individual sealing required.

Septic service

Tahoe Donner

$400/yr ($33/mo) — Annual pump-out estimate. Tahoe Donner is not served by Truckee Sanitary District. Verified quote pending (s3-31a).

Glenshire

$400/yr ($33/mo) — Annual maintenance estimate. Not on Truckee Sanitary District sewer service.

Truckee Proper

$0 — Connected to Truckee Sanitary District. No septic cost.

Northstar

$0 — Connected to Northstar public sewer system. No septic cost.

What we don't claim

These are 2026 estimates. HOA fees, insurance premiums, propane prices, and contractor rates all change. We update verified figures annually or when notified of changes.

Individual properties vary. Lot size affects snow removal and defensible space costs. Condo HOA structures at Northstar differ significantly from SFH. Pre-existing propane contracts, solar installations, and property-specific factors all affect the actual figure.

Estimated figures are marked. The “est.” badge on a cost row means we're working from regional averages, not a verified local quote. We are actively gathering quotes to upgrade all estimates to verified status.

This is not comprehensive. We cover the eight largest recurring hidden costs. We do not model maintenance reserves, capital expenditure cycles, HOA special assessments, or one-time costs like well drilling or chimney lining.

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