Laboratory costs typically represent 8-15% of practice turnover, making them one of your largest expense categories. How you account for these laboratory expenses affects both your tax position and the accuracy of your business reporting.

Many practice owners treat all lab costs as general expenses, but this approach can distort your true profit margins and create compliance issues with your accountant.

Laboratory Costs as Cost of Sales

In most cases, laboratory costs should be classified as cost of sales rather than general practice expenses. This applies when the lab work directly relates to patient treatment you've invoiced.

Cost of sales treatment means these expenses are matched against the revenue from the specific treatments. For example, if you charge a patient £400 for a crown and pay the dental lab £120, that lab cost becomes part of your cost of sales for that treatment.

This matching principle gives you clearer gross profit margins and helps with pricing decisions. Your gross profit should reflect the true profitability after direct treatment costs.

When Lab Costs Are General Expenses

Some laboratory expenses don't relate to specific patient treatments and should remain as general expenses:

  • Equipment repairs and maintenance at your lab
  • Lab consumables used for practice management (models, trays)
  • Training courses at laboratory facilities
  • Lab equipment depreciation if you have an in-house facility

The distinction matters because cost of sales affects your gross profit calculation, while general expenses impact your net profit after all overheads.

Record Keeping for Lab Expenses

Proper records for laboratory expenses should include:

  • Original lab invoices with VAT breakdown
  • Patient reference numbers linking lab work to treatments
  • Delivery notes confirming receipt of work
  • Payment records showing when invoices were settled

Many practices use practice management software to link lab costs directly to patient records. This creates an audit trail and helps with cost analysis by treatment type.

Managing Laboratory Costs Effectively

Understanding your lab costs as a percentage of revenue helps with benchmarking and pricing. Most practices should see lab costs between 8-15% of turnover, varying by treatment mix.

Higher percentages might indicate pricing issues, while very low percentages could suggest you're not offering enough lab-based treatments.

Regular review of lab invoices helps identify billing errors and ensures you're getting value for money. Some practices negotiate monthly payment terms or volume discounts with their preferred laboratories.

Year-End Considerations

At year-end, ensure all laboratory costs for work delivered are included in your accounts, even if invoices arrive after your accounting date. This prevents profit distortion across accounting periods.

For significant outstanding lab work, your accountant may need to accrue estimated costs to match them with related patient revenue.

If you're considering practice acquisition financial due diligence, accurate lab cost accounting becomes crucial for potential buyers assessing your true profit margins.

VAT Treatment of Laboratory Costs

VAT on dental laboratory costs requires careful handling. Dental treatment itself is VAT-exempt, but the lab work you purchase is a standard-rated input. If your practice is VAT registered — typically because you offer facial aesthetics or other taxable services — you can recover VAT on lab costs through your VAT return.

Practices that aren't VAT registered absorb the VAT as part of the cost. This makes the gross lab invoice the relevant figure for your accounts. When comparing costs between labs, always compare VAT-inclusive prices if you can't reclaim.

For practices with mixed NHS and private work, ensure your accountant applies the correct partial exemption method if you're VAT registered. This determines what proportion of input VAT on shared costs (including lab work) you can recover.

Choosing Between In-House and External Labs

Some practices invest in in-house laboratory facilities, particularly for same-day restorations using CAD/CAM technology. The accounting treatment differs significantly from external lab costs:

  • Equipment — capitalised and depreciated, with capital allowances claimed over the asset's life.
  • Materials — treated as consumables and expensed when used.
  • Technician salaries — staff costs, not cost of sales.
  • Maintenance — general practice expenses.

The financial case for in-house lab work depends on volume. Practices producing 15+ units per week often break even compared to external costs, with higher volumes generating clear savings. Below that threshold, external labs usually offer better value.

Laboratory cost accounting might seem straightforward, but proper classification and timing can significantly impact your financial reporting and tax position. When in doubt, speak to a specialist dental accountant who understands the nuances of practice-specific expenses.