The Massachusetts septic tax credit and AquiFund, explained

The Massachusetts Title 5 tax credit

The tax credit is the bigger of the two in dollar terms. For a home you own and occupy as your principal residence, it covers 60% of eligible repair or replacement costs, on up to $30,000 of spending. That works out to a maximum credit of $18,000. You claim up to $4,000 in any single year and carry the remainder forward for up to five years, so a full $18,000 credit plays out over several tax years rather than all at once.

Since tax year 2024, the credit has covered not just failed-system repairs and replacements but also upgrades required by a watershed permit and sewer connections. You claim it on Schedule SC with your Massachusetts return, and you will need the Certificate of Compliance from your board of health. Two limits matter most on the Cape: it is a credit against state income tax, not a cash rebate, and it is only for a principal residence, so the many seasonal and second homes here do not qualify. We are not tax advisors, so confirm the details with Schedule SC and your tax preparer.

Barnstable County's AquiFund loan

AquiFund, the county's Community Septic Management Loan Program, solves the other half of the problem: the up-front cash. It makes betterment loans of up to 20 years, and the rate depends on the work. Septic repairs, replacements, and nitrogen-reducing I/A upgrades are financed at 4%. The income-tiered 0% and 2% rates that sometimes get quoted apply only to new sewer connections, not to septic system work, so plan on 4% for a replacement. There is no published loan cap. The program reports lending on the order of $52.5 million across more than 4,550 systems, so it is well established, not a pilot.

Because it is a betterment loan, repayment is added to your property tax bill and stays with the property. Details and current terms are on the county's AquiFund page.

Two worked examples

A $30,000 conventional replacement, principal residence. The tax credit returns 60% of $30,000, the full $18,000, claimed at up to $4,000 a year over five years. A 20-year AquiFund loan at 4% covers the up-front cost so you are not writing a $30,000 check. Net of the credit, your true cost is around $12,000, spread over time.

A $40,000 job on a hard site. The credit still maxes at $18,000 (60% is capped at $30,000 of spending), so your net is about $22,000. AquiFund again spreads the financing over 20 years at 4%. The credit does not scale past $30,000 of cost, which is worth knowing before you assume a bigger job means a bigger credit.

These examples are illustrative, not a promise of your result. Your credit depends on your tax situation and your loan on your eligibility. Confirm both with the sources above and a professional.

On the South Shore

AquiFund is a Barnstable County program, so it does not reach Plymouth County. The statewide tax credit still applies, and towns run their own loan programs. Our Plymouth page covers how that works there.

Putting it to work

The programs only matter once you know your number. See the replacement cost guide for what a Cape job runs, the replacement page for how it works, and the Title 5 guide for the full process. When you are ready, we connect you with a licensed local contractor at no cost.