Non-Dependant Deductions and Adult Children: Cornwall Council Tax Reduction

What a Non-Dependant Deduction Is

If another adult lives in your Cornwall home — an adult child, a sibling, a friend, a parent — Cornwall Council assumes they contribute towards the council tax and reduces your Council Tax Support by a fixed weekly amount. This happens automatically, regardless of whether they actually hand you any money.

The deduction is based on the non-dependant's gross weekly income and whether they work 16 or more hours a week. It comes off your award, not theirs — your bill goes up even though the assumption is that they're helping pay it.

The 2026/27 Deduction Rates

Cornwall applies these weekly deductions for the current tax year:

Not in paid work, or working under 16 hours per week: £5.00

Working 16+ hours, earning under £266 per week: £5.20

Working 16+ hours, earning £266–£462.99 per week: £10.60

Working 16+ hours, earning £463–£576.99 per week: £13.30

Working 16+ hours, earning £577 or more per week: £15.95

If two non-dependants live together as a couple, Cornwall applies a single deduction based on their combined income — not two separate deductions.

When No Deduction Is Taken

Cornwall doesn't apply a non-dependant deduction if:

• The main claimant or their partner receives DLA (care component), PIP (daily living), or Attendance Allowance
• The claimant is registered severely sight-impaired
• The non-dependant is under 18
• The non-dependant is a full-time student
• The non-dependant is a paid care worker provided by a charity or commercial agency

The disability exemption is significant. If you receive PIP daily living, no deduction is taken from your award regardless of how much your adult child earns.

The Adult Child Moving Home Scenario

An adult child returning to your home triggers two things at once. First, if you had the 25% Single Person Discount, you lose it — your base bill jumps by a third. Second, Cornwall adds a non-dependant deduction to your Council Tax Support calculation.

The combined effect can be dramatic. A parent on maximum Council Tax Support who loses the Single Person Discount and gains a £10.60 weekly non-dependant deduction could see their bill rise by £50–£70 a month, depending on the property band.

If the child is unemployed and not working, the deduction is the lower £5.00 rate. If they're earning, it climbs. Either way, you must report the change to Cornwall Council within 21 days. The adult child may also want to apply for their own Council Tax Support if they're liable for the bill elsewhere, or explore whether the household qualifies for Exceptional Relief if the combined charges become unaffordable.

The Cornwall Council Tax Reduction guide includes the full non-dependant deduction schedule and explains which exemptions cancel the deduction entirely.

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