When you get married or enter a civil partnership in Ireland, Revenue allows three different bases of assessment. The one you use will affect:
- How your income is taxed
- How your tax credits are used
- Whether you can share unused allowances.
Many people misunderstand how these options work, so we’ve created a guide to make it easier to ensure you’re selecting the option that’s right for you and your spouse/civil partner.
The 3 options at a glance:
You can be taxed under:
- Joint assessment (default and most commonly used)
- Separate assessment
- Separate treatment
Each works differently in practice.
- Joint assessment (how most couples are taxed)
This is Revenue’s default once you notify them of your marriage or civil partnership and will be applied automatically unless you elect otherwise.
How it works
- One person becomes the assessable spouse
- The couple is effectively taxed as a single unit
- Tax credits and rate bands can be shared and allocated between you both.
2026 tax bands
- Standard rate band (single): €53,000
- Maximum band for married couples: €88,000
- The increase depends on the lower earner’s income
👉 The lower earner can increase the band by up to €35,000.
Example (clear breakdown)
Couple:
- Person A earns €70,000
- Person B earns €20,000
Under joint assessment:
- Base band: €53,000
- Increase: €20,000 (limited to lower earner’s income)
- Total standard rate band: €73,000
👉 This means:
- €73,000 taxed at 20%
- Remaining €17,000 taxed at 40%
Why this matters
Without joint assessment:
- Person A would only have €53,000 at 20%
- More of their income would be taxed at 40%
👉 Joint assessment reduces higher-rate tax exposure.
When it works best
Joint assessment is most beneficial where:
- One person earns significantly more than the other
- One person has unused tax credits or rate band.
- Separate assessment (a middle ground)
This option sits between joint assessment and full separation.
How it works
- Each spouse is taxed separately during the year
- But after the year ends:
- Unused tax credits can be transferred
- Some unused standard rate band can be transferred
👉 The transfer is not automatic, it happens after the year is reviewed.
Example
Couple:
- Person A earns €60,000
- Person B earns €10,000
During the year:
- Each taxed separately
After year-end:
- Person B may have unused credits
- Some of these can be transferred to Person A
👉 Result:
- Some tax saving
- But less efficient than full joint assessment
When it might be used
- Couples who want some independence in tax affairs
- Situations where incomes fluctuate year to year
- Separate treatment (treated like two single people)
This is the simplest option but usually the least beneficial.
How it works
- Each person is taxed completely independently
- No sharing of tax credits or standard rate band
Example
Using the same couple:
- Person A earns €70,000
- Person B earns €20,000
Each is taxed as single:
- Person A:
- €53,000 at 20%
- €17,000 at 40%
- Person B:
- €20,000 at 20%
- Unused credits/band cannot be transferred
👉 Result:
- More income taxed at 40% overall
- Lost opportunity to use unused allowances
Key differences (quick comparison)
| Feature | Joint Assessment | Separate Assessment | Separate Treatment |
| Share tax credits | Yes | Limited | No |
| Share rate band | Yes | Limited (after year-end) | No |
| Admin complexity | Moderate | Moderate | Low |
| Typically best for tax savings | Yes | Sometimes | Rarely |
👉 Practical takeaway:
The benefit of marriage or civil partnership for tax purposes comes mainly from the ability to share unused credits and rate bands and that only happens under the right assessment option.
Need help?
If you’re married or in a civil partnership and unsure which option applies or whether you’re using the system efficiently, it’s worth checking.
At FastTax.ie, we help make sure you’re not paying more tax than you need to.
See also:
