An Antioch purchase budget needs a collecting agency and a payment route beside every charge. A tax-roll sewer charge, a City utility account, a public special tax and a private association assessment can all appear in the same ownership decision. They pay for different obligations. Combining the documents carefully matters as much as comparing the advertised monthly amounts.
This guide develops the ownership questions in the Antioch guide through dated local records and an original partial cost model. The two usage cases below are hypothetical accounts, not inspected properties or quoted household budgets. No private tax statement, association financial package, insurance quote or contractor estimate was supplied. Those missing inputs remain open rather than becoming invented averages.
Build the address file before comparing totals
Start with the parcel number, dwelling configuration and actual service accounts. A detached house with accessory accommodation requires questions about which dwellings share a meter and how providers classify the account. An attached home requires questions about charges paid collectively. Two equal utility payments are not directly comparable if one includes services that the other owner pays separately.
For each finalist, collect a full year of available bills and note occupancy, irrigation and any unusual vacancy or leak. Request account identifiers with personal information protected. A seller’s consumption history provides context for that household; it does not predict another household’s habits. Keep actual historical spending and a buyer’s forward budget in separate columns so the assumptions remain visible.
Use the same review date for both candidates. If one seller supplies last year’s charges and another supplies the current schedule, update the older inputs before ranking the homes. Where a source is only a proposed schedule, retain its proposal label. An increase under consideration and an adopted recurring charge belong in different budget columns.
Read tax-roll lines as individual obligations
Contra Costa County explains that the property tax bill separates the basic one-percent tax, additional voter-approved taxes and applicable special taxes, assessments, fees and charges. Its allocation lookup currently identifies fiscal year 2025–26. That historical allocation display is not a complete current cost estimate for a new buyer or a substitute for the candidate’s actual bill.
Transcribe the bill line by line, recording the responsible agency and the period covered. Then mark which entries are already included in a lender’s payment estimate. A worksheet that begins with the entire annual tax bill and adds the same district charge again exaggerates ownership cost. A worksheet that uses only the basic tax percentage can omit relevant parcel charges.
The County’s new-owner guidance also distinguishes a supplemental bill from the regular secured bill. The supplemental bill is additional and goes to the owner even when the lender maintains an impound account. Plan the timing of that possible first-year cash requirement separately from the recurring annual budget; obtain a buyer-specific estimate rather than simply repeating the seller’s existing assessed-value bill.
Ask the lender how the estimate treats the purchase, direct assessments and any supplemental obligation. Reconcile the response with the escrow figures and actual agency records. Keep one-time acquisition cash in its own section. Otherwise a first-year tax adjustment may look like a permanent monthly expense, while a recurring assessment can disappear inside a closing statement.
A public district proposal does not establish private HOA dues
A real local example illustrates the document problem. A February 24, 2026 Antioch staff report recommends adding parcel 057-050-029 to Community Facilities District 2022-01 for public services. That is a public financing record, not an association budget. The packet contains an unsigned proposed resolution and inconsistent district wording in an attachment; it does not by itself establish the final recorded annexation or a candidate’s current levy.
Use such a lead to request the final action, applicable recorded boundary and current parcel charge. Do not spread a project-level figure across unrelated nearby houses. The development name, a similar streetscape or a nearby new subdivision is insufficient to establish which charge belongs to the candidate. Trace the actual parcel and applicable levy documents.
For an association, request the current budget, dues statement, reserve information, approved special assessments and maintenance documents. Identify whether the payment covers water, insurance, private streets or exterior components. A lower due can leave more work with the owner; a higher due can include an expense otherwise budgeted separately. Neither comparison can be settled by the due alone.
Separate ordinary recurring dues, a temporary assessment and an owner’s own capital reserve. Record the assessment’s payment schedule and any documented transfer treatment without assuming the buyer or seller automatically bears it. Have the appropriate transaction professional confirm the actual agreement. No association’s financial health or particular allocation of maintenance duties is evaluated here.
Model water consumption without pretending to quote a house
The calculation below holds the hypothetical meter, customer class and pressure zone constant, then changes consumption. It isolates one decision: how sensitive selected water charges are to usage. Both cases assume the same monthly usage throughout twelve months. They are arithmetic illustrations rather than seasonal forecasts, full utility bills or estimates for any named address.
Original Antioch water and sewer reconciliation worksheet
Checked October 26, 2026. Hypothetical City single-family Zone I account, 5/8 × 3/4-inch meter. Inputs: adopted City fee schedule, pages 13, 15 and 17: water $4.71/HCF for the first 11 HCF, then $7.57/HCF; monthly meter maintenance $29.30; single-family sewer collection $20.50/month. One HCF is 100 cubic feet.
| Component | Case A: 8 HCF/month | Case B: 16 HCF/month | Treatment |
|---|---|---|---|
| Monthly water arithmetic | $29.30 + (8 × $4.71) = $66.98 | $29.30 + (11 × $4.71) + (5 × $7.57) = $118.96 | Selected maintenance and consumption only |
| Annual selected water charges | $803.76 | $1,427.52 | Twelve identical assumed months |
| Annual City single-family sewer collection | $246.00 | $246.00 | $20.50 × 12; separate from District treatment charge |
| Delta Diablo FY2026–27 residential charge | $557.48 | $557.48 | Verify actual classification and tax-roll entry before inclusion |
| Selected three-component annual subtotal | $1,607.24 | $2,231.00 | Partial illustration only; difference $623.76 |
District support: June 10, 2026 adoption account and the linked April 23 presentation, residential rate table. The presentation’s older City collection figure is superseded by the City schedule used above.
Excludes other applicable account charges, sweeping, stormwater, refuse, energy, taxes, insurance, association charges, maintenance and acquisition costs. If starting with the complete tax bill, identify any included Delta Diablo charge and count it once. Confirm actual meter, zone, dwelling classification, billing period and every additional item with providers.
Changing eight units to sixteen does not simply double the illustrated water payment: the fixed component stays constant while some additional consumption enters a higher tier. Conversely, dividing the subtotal by occupants would not establish a provider’s per-person tariff. The model describes a particular set of account assumptions, not a rule for allocating a shared property’s bill.
For an actual house, replace the assumed usage with a documented pattern and confirm the provider’s applicable zone and meter. Do not automatically use the model for a larger meter, a multifamily classification or another zone. Preserve the original bill units when entering readings. Mixing cubic feet with hundreds of cubic feet can create a far larger error than a modest rate change.
Reconcile collection, treatment and the payment channel
Delta Diablo reports that its Board adopted the fiscal 2026–27 charges and tax-roll report on June 10, 2026; most customers pay the District charge through property taxes. Its adoption page links an earlier April presentation. Check both the action date and the date printed on supporting material rather than assuming every figure in a linked presentation has been refreshed.
The City and District components in the worksheet serve different purposes. When reviewing a seller’s records, identify both obligations and where each is paid. Future maximum district increases are not an instruction to insert an automatic realized increase into every forecast. Show any scenario as a scenario, and replace it when the applicable annual action and candidate charge are known.
Complete the private costs before choosing a finalist
Energy bills need the same configuration check as water. Record which equipment actually serves the house, any accessory space, a pool and vehicle charging. Ask for the applicable account and tariff evidence before extrapolating a seller’s payment. If the property includes a solar agreement, obtain the agreement and current statements; a panel visible from the street does not establish ownership, remaining payments or the buyer’s future net energy cost.
Assign an unresolved input to a person and a document. The association manager can supply its current payment schedule, the provider can clarify account classification, and a contractor can price an identified scope. Keep the requested response date beside the gap. That turns an incomplete spreadsheet into an actionable purchase investigation rather than a misleadingly precise total.
Obtain address-specific insurance evidence and quotes for work identified by the inspections. Separate scheduled servicing from a component replacement, and record whether the owner or association maintains each item. A proposed improvement needs its own project budget; it should not silently become an assumed recurring cost of owning the current configuration.
Present the final comparison with verified recurring charges, one-time acquisition cash, owner maintenance reserves and unresolved inputs shown separately. Date each amount and retain the supporting document. The financing guide and Contra Costa County guide provide the wider planning context while the actual parcel and account evidence determine the local comparison.
