Bonding
What would this cost your household?
What a big borrowed project costs your household, per year, over the life of the loan. Start from the school or road example, or type your own figure.
Estimates from public data, not your bill.
Example figures from public discussion; every number here is editable.
The state is expected to cover most of the school project's total cost; this models only the town's bonded share.
- Town bill today
- This borrowing
About $386 a year for 20 years on a $300,000 home — roughly $7,043 over the life of the loan.
Change the assumptions
Level annual debt service
$6,918,853
every year for 20 years
Year 1 cost for this home
$386
1.84 ($386 a year on a $300,000 home)
| Total repaid over the term | $138,377,060 |
| Of which interest | $48,377,060 |
| Total for a $300,000 home over 20 years | $7,043 |
Year by year
| Year | Grand list | Mills | This home pays |
|---|---|---|---|
| 1 | $3,760,169,400 | 1.84 | $386 |
| 2 | $3,797,771,094 | 1.82 | $383 |
| 3 | $3,835,748,805 | 1.80 | $379 |
| 4 | $3,874,106,293 | 1.79 | $375 |
| 5 | $3,912,847,356 | 1.77 | $371 |
| 6 | $3,951,975,829 | 1.75 | $368 |
| 7 | $3,991,495,588 | 1.73 | $364 |
| 8 | $4,031,410,544 | 1.72 | $360 |
| 9 | $4,071,724,649 | 1.70 | $357 |
| 10 | $4,112,441,896 | 1.68 | $353 |
| 11 | $4,153,566,315 | 1.67 | $350 |
| 12 | $4,195,101,978 | 1.65 | $346 |
| 13 | $4,237,052,997 | 1.63 | $343 |
| 14 | $4,279,423,527 | 1.62 | $340 |
| 15 | $4,322,217,763 | 1.60 | $336 |
| 16 | $4,365,439,940 | 1.58 | $333 |
| 17 | $4,409,094,340 | 1.57 | $330 |
| 18 | $4,453,185,283 | 1.55 | $326 |
| 19 | $4,497,717,136 | 1.54 | $323 |
| 20 | $4,542,694,307 | 1.52 | $320 |
How it works
A bond is not a cost the town pays once. It is a level annual payment, made every year for the term, funded by the property tax like everything else. This model turns a borrowing amount into the two numbers a taxpayer actually experiences: mills on the grand list, and dollars on one home’s bill.
- Level annual debt service. The standard level-payment formula, the same
one behind a mortgage:
A = p × i / (1 − (1 + i)^−t). The payment is flat for the whole term. - Mills. Each year’s payment divided by that year’s grand list. The grand list grows by the growth input, so the same flat payment takes a slightly smaller bite each year — which is why the mills fall over the term rather than staying level.
- Your share. Your home’s assessed value (70% of market value in Connecticut) times that year’s mills.
The presets are examples, not modes. They set the borrowing amount and nothing else. If you think the real figure is different, type it in — the arithmetic works the same either way.
Simplifications
- Level payments. Connecticut towns often borrow with level-principal bonds instead, where payments start higher and decline. Level payment is the more conservative shape for a per-year figure and the easier one to reason about; a level-principal issue would cost more in the early years and less later, for a slightly lower total.
- One issue, drawn at once. Real projects are bonded in tranches over several years, often with short-term notes first. That delays the start and spreads the ramp.
- No existing debt. This shows the cost of this borrowing only. It is not the town’s total debt service, and it does not account for old debt rolling off, which frequently offsets part of a new issue.
- The grand list grows smoothly. Real grand lists move in steps at revaluation and with new construction.
- Nominal dollars. Totals over the term are added up without discounting, so the year-20 dollar counts the same as the year-1 dollar. That overstates the real burden of the later years.
- The state’s share of a school project is not modelled. Only the town’s bonded share is.
What would change these numbers most
The amount borrowed and the term, in that order. The interest rate matters less than people expect over a 20-year level payment: a full point costs roughly the same as adding a couple of million to the principal.
Sources for this model
Every number this model uses, with where it came from and the date it applies to. Values marked estimate are assumptions, not published figures.
- assessment_ratio · Connecticut official70% as of 2026-01-01CGS 12-62a — uniform assessment rate — Connecticut General Assembly , 2026-01-01Connecticut assesses real property at 70% of market value. Assessed value = market value * 0.70.
- grand_list_total_net · Enfield official$3,722.94M as of 2025-10-01Net Grand List by Town, 2011-present — CT Office of Policy and Management (data.ct.gov) , 2026-08-31Total net grand list $3,722,936,734.
- mill_rate_real_estate · Enfield reported33.11 mills as of 2026-07-01Enfield Town Council Approves 2026-27 Budget, Increases Taxes — Patch , 2026-05-14FY2027 adopted rate. OPM's mill rate dataset runs through FY2026 only, where Enfield's rate is 31.50; replace this entry with the official figure once OPM publishes FY2027.
- road_plan_total · Enfield reported$40M as of 2026-05-12Enfield raises taxes, but the bigger fight is just beginning — Enfield Things , 2026-05-12The road plan figure in public discussion. Used as the 'roads example' preset value only; the input is editable.
- school_bond_town_share · Enfield reported$90M as of 2026-05-12Enfield raises taxes, but the bigger fight is just beginning — Enfield Things , 2026-05-12Approximate town share of the elementary school project; the project total is around $500M with the state covering most of it. Used as the 'schools example' preset value only; the input is editable.
Changes to this model
- 2026-08-31 Published The borrowing model, for the school project, the road plan, or any amount you enter.