MIC / Agreed Capacity
Maximum Import Capacity
Network ChargesThe maximum electrical demand (in kVA) your connection is designed to handle, set in your connection agreement with the DNO - this value directly determines your DUoS capacity charges and TNUoS TDR band.
Maximum Import Capacity (MIC) is the maximum power (in kVA) that your electricity connection is designed to supply at any moment. It's agreed between you and the DNO when the connection is established and recorded in your connection agreement.
Why MIC matters: MIC directly affects two charges on your bill:
- DUoS Capacity Charge - For Site Specific tariffs: MIC × p/kVA/day × days
- TNUoS TDR Band - Since April 2023, your average MIC over the 24-month window before each price control sets which fixed band you sit in for that whole period (DCUSA Schedule 32 ¶4.1, ¶4.5)
Example calculation:
- MIC: 200 kVA
- Capacity Rate: 1.50 p/kVA/day
- 30-day month
- Charge: 200 × 1.50 × 30 = 9,000 pence = £90.00
TNUoS TDR band thresholds (NESO TDR Guidance):
RIIO-3, 1 April 2026 to 31 March 2031 (Table 1b):
| Voltage | Band 1 | Band 2 | Band 3 | Band 4 |
|---|---|---|---|---|
| LV | up to 90 kVA | 91-150 kVA | 151-250 kVA | over 250 kVA |
| HV | up to 500 kVA | 501-1,100 kVA | 1,101-2,000 kVA | over 2,000 kVA |
| EHV | up to 3,500 kVA | 3,501-11,000 kVA | 11,001-20,000 kVA | over 20,000 kVA |
RIIO-2, 1 April 2023 to 31 March 2026 (Table 1a, superseded):
| Voltage | Band 1 | Band 2 | Band 3 | Band 4 |
|---|---|---|---|---|
| LV | up to 80 kVA | 81-150 kVA | 151-231 kVA | over 231 kVA |
| HV | up to 422 kVA | 423-1,000 kVA | 1,001-1,800 kVA | over 1,800 kVA |
| EHV | up to 5,000 kVA | 5,001-12,000 kVA | 12,001-21,500 kVA | over 21,500 kVA |
A MIC exactly on a threshold falls in the lower band.
The MIC data access problem: A common industry challenge is obtaining accurate MIC data before receiving the first DUoS bill. Unlike meter readings that flow through standard industry data channels, MIC is connection data stored by DNOs but not routinely shared via systems like ElectraLink/ECOES.
Options for obtaining MIC data:
| Source | Reliability | Speed | Notes |
|---|---|---|---|
| Customer's connection agreement | High | Varies | Customer may not have it |
| Previous supplier's DUoS invoice | High | Varies | Shows capacity charged |
| Direct DNO request | High | 5-10 days | May need customer authorisation |
| ElectraLink/ECOES | Partial (~60%) | Immediate | Often outdated |
| First DNO bill | 100% | After billing cycle | Most common "true-up" approach |
Why ElectraLink data is often incomplete: MIC isn't a mandatory field in standard industry data flows (DTS). The switching and settlement systems were built around meter readings, not connection agreements. Many historical connections pre-date digital systems and were never properly captured.
Changing your MIC: If your requirements change, you can request a capacity increase or decrease from your DNO. This may involve:
- Application fee
- Possible network reinforcement costs (if increasing)
- New connection agreement
- Updated DUoS capacity charges from the effective date (the TNUoS TDR band holds to the end of the price control)
Bill validation tip: If the capacity charged on your DUoS invoice doesn't match your connection agreement, this is a billing error. Also check your TNUoS TDR band against the average MIC you held over the allocation window (1 May 2022 to 30 April 2024 for RIIO-3), not the MIC you hold today: Schedule 32 ¶4.5 fixes the band to 31 March 2031. A wrongly allocated band is a ¶7 dispute, rebated up to six years back (¶7.17).
Example
Connection Agreement: Maximum Import Capacity = 150 kVARelated terms
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