limited company mortgage calculator

What this limited company mortgage calculator does

This tool helps you quickly model a buy-to-let purchase through a limited company (usually an SPV). In one click, it estimates:

• Loan amount and LTV based on purchase price and deposit
• Monthly mortgage payment (interest-only or repayment)
• Rental stress-test capacity using a lender-style ICR formula
• Estimated first-year pre-tax and post-tax cash flow

That makes it useful for early-stage deal screening before you speak to a mortgage broker or lender.

How lenders usually assess limited company buy-to-let loans

1) Loan-to-value (LTV)

LTV is the mortgage amount divided by the property value. Many limited company buy-to-let products cap borrowing at a specific LTV, commonly around 75%, though this varies by lender and product.

2) Interest coverage ratio (ICR)

ICR compares rental income to stressed mortgage interest. Lenders test whether expected rent covers a notional interest cost at a stress rate, not necessarily your pay rate. A common rule of thumb:

Maximum loan by rent = Annual rent ÷ (Stress rate × Required ICR)

If your required loan is above this limit, the case may fail affordability even if the deal looks profitable at your actual mortgage rate.

3) Company and director profile

Most lenders require a clean company structure, acceptable SIC code, and reasonable director background. Some prefer pure SPVs focused on property activity, while others accept trading companies under specific conditions.

Repayment vs interest-only for a limited company mortgage

• Interest-only: Lower monthly payments and often stronger short-term cash flow, but principal remains outstanding until exit/refinance/sale.
• Repayment: Higher monthly payments, but debt reduces over time and long-term equity build can be stronger.

The right option depends on your strategy: cash flow optimization, portfolio scaling, long-term deleveraging, or planned disposal timelines.

Worked example (simple)

Suppose you buy at £250,000 with a 25% deposit (£62,500), borrow £187,500, and expect £1,450 monthly rent. If the lender stress rate is 5.5% and required ICR is 125%, the rent-based maximum loan may be lower or higher than your requested borrowing depending on local rent levels.

This is why rent quality matters as much as purchase price. Two similar properties can have very different lending outcomes if one commands stronger rent.

How to improve borrowing power and deal resilience

• Increase deposit to reduce LTV and monthly payment pressure
• Target stronger rent-to-price areas to improve ICR headroom
• Lower financing costs by comparing products and fees carefully
• Keep company records and director credit profile clean
• Stress-test for higher rates and void periods, not just headline yield

Common mistakes investors make

• Using only headline yield and ignoring lender stress criteria
• Ignoring one-off costs (fees, legal costs, valuation, refurb scope)
• Confusing accounting profit with cash flow timing
• Choosing repayment structure without a clear exit strategy
• Assuming all limited company lenders use identical rules

Frequently asked questions

Is this calculator a formal mortgage offer?

No. It provides estimates for planning. Actual terms depend on lender underwriting, valuation, credit checks, company structure, and market conditions.

Does it include every allowable tax adjustment?

No. It gives a simplified first-year estimate. Real corporation tax outcomes depend on full accounts, allowable expenses, and professional tax treatment.

Can I use it for HMOs or multi-unit properties?

Yes for rough estimates, but specialist assets often have different rent assumptions, lender policy, and stress rules. Confirm with a specialist broker.

Important: This page is educational and not financial, legal, or tax advice. Always verify numbers with a regulated mortgage broker and a qualified accountant before committing to any property purchase.