Do you know what your 2025–26 tax code means? It affects how much tax is taken from your pay or pension. Check now to make sure you're on the right code and not overpaying! Here's what the letters and numbers really mean.

You can find your tax code:

• by checking your tax code for the current year online – you’ll need to sign in to or create an online account
• on the HMRC app
• on your payslip
• on a ‘Tax Code Notice’ letter from HMRC if you get one

The tax codes are updated annually. The basic personal allowance for the 2025-26 tax year is £12,570. The corresponding tax code for an employee entitled to the standard tax-free Personal Allowance 1257L. This is the most common tax code and is used for most people with one job and no untaxed income, unpaid tax or taxable benefits (for example a company car).

There are a lot of other numbers and letters that can appear in your tax code. For example, there are letters that show where an employee is claiming the marriage allowance (M) or where their income or pension is taxed using the Scottish rates (S). If your tax code numbers are changed this usually means your personal allowance has been reduced.

There are also emergency tax codes (W1 or M1) which can be used if a new employee doesn’t have a P45. These codes mean that an employee’s tax calculation is based only on what they are paid in the current pay period.

If your tax code has a 'K' at the beginning this means that deductions due for company benefits, state pension or tax owed from previous years are greater than your personal allowance. However, the tax deduction for each pay period can’t be more than half your pre-tax pay or pension.

It is important to check your 2025-26 tax code to ensure the correct information is being used. 
 

Couples who jointly own rental property are usually taxed 50:50, even if they own different shares. But if you're married or in a civil partnership, Form 17 lets you split income based on actual ownership—provided you meet HMRC's rules.

The standard tax treatment for couples living together, whether married or in a civil partnership, is that property income held jointly is split 50:50, regardless of the actual ownership proportion.

However, if the ownership is unequal and the couple wishes to have the income taxed in line with their respective shares, they must notify HMRC and provide evidence of the unequal beneficial interests in the property. This is done by submitting Form 17, which declares the beneficial interests in joint property and income.

A Form 17 declaration can only be made by spouses or civil partners living together who own property in unequal shares, with the income allocated in proportion to these shares. Couples who are separated or in other types of relationships are not eligible to submit a Form 17 declaration.

The declaration is only valid if both partners agree. If one partner disagrees, the income will continue to be split 50:50, regardless of the ownership structure.

Once submitted, a Form 17 declaration remains in effect until there is a change in the couple's status, such as separation or divorce, or a change in the ownership structure. If either of these occurs, the 50:50 income split will be reinstated.

There are specific situations in which Form 17 cannot be used, such as when spouses or civil partners own property as beneficial joint tenants, income from shares in a close company or for partnership income.

In cases where property is owned in unequal shares, submitting a Form 17 declaration can offer tax benefits under certain circumstances.

Making Tax Digital for Income Tax (MTD for IT) will become mandatory in phases from April 2026. If you’re self-employed or a landlord earning over £50,000, get ready for quarterly updates, digital record keeping, and a new penalty system.

Initially, MTD for IT will apply to businesses, self-employed individuals, and landlords with an annual income exceeding £50,000. From 6 April 2027, the rules will extend to those with an income between £30,000 and £50,000. A new system of penalties for late filing and late payment of tax will also be introduced.

In the Spring Statement 2025, the government confirmed that MTD for IT will apply to sole traders and landlords with income over £20,000 starting in April 2028. The government will also explore how to treat those with income below the £20,000 threshold.

Starting in April 2025, HMRC will begin writing to taxpayers whose 2023-24 self-assessment returns show that their total income from self-employment and property is approaching or exceeds £50,000. These letters will notify them of their obligation to use MTD for IT starting in April 2026.

Although MTD for IT becomes mandatory in 2026, you can opt to sign up voluntarily before then. This allows you to help HMRC test and refine the system while also familiarising yourself with the new rules. While signing up is currently voluntary, there are specific eligibility requirements, and not all taxpayers will qualify. If you are eligible, you can sign up on GOV.UK.

If you volunteer to participate in testing the MTD for IT service, the new penalties for late submissions and late payments will apply. This will replace the existing penalties for the relevant tax years. No penalties will apply for the quarterly updates for volunteers in 2024-25 or 2025-26.

If you're self-employed, lenders may require an SA302 and tax year overview as proof of earnings for mortgages or loans. These documents verify income declared on your self-assessment tax return and are easily accessible via HMRC. Learn how to obtain them.

The use of these forms has become more widespread since mortgage regulations began requiring self-employed individuals to provide verifiable evidence of income. The SA302 serves as proof of income for the last four years of self-assessment tax returns.

The SA302 document provides a detailed breakdown of the income reported on the taxpayer’s self-assessment tax return, including commercial versions of the tax return. Meanwhile, the tax year overview confirms the tax due based on the return submitted to HMRC, showing any payments made, and cross-referencing the Tax Calculation with HMRC’s records.

Self-assessment taxpayers can request an SA302 tax calculation through HMRC’s online service. After submitting an online tax return, it typically takes around 72 hours for the documents to become available for printing.

Most lenders will accept an SA302 printed directly from online accounts or from the commercial software used to submit tax returns. HMRC has been actively working with the Council of Mortgage Lenders and its members to expand the number of lenders willing to accept self-serve copies of these documents as valid proof of income.

Since April 2020, landlords can no longer deduct mortgage interest as an expense. Instead, tax relief is capped at 20%. This change affects UK and non-UK resident landlords, trustees, and partnerships but excludes companies. Learn how this impacts your tax bill.

In April 2017, new rules were introduced that limited the tax relief on mortgage costs for residential landlords to the basic rate of tax. This restriction on finance costs was phased in over several years and was fully implemented by 6 April 2020. As a result, all finance costs, including mortgage interest on rented properties, are no longer allowed as expenses. Any available tax relief is now capped at the basic tax rate of 20%.

Finance costs includes interest on mortgages, loans (including those for furnishings), overdrafts, alternative finance returns, mortgage fees, and other related costs, such as discounts, premiums, and disguised interest. However, no relief is granted for capital repayments of a mortgage or loan.

You will be affected by this restriction if you are:

• A UK resident individual letting residential properties in the UK or abroad.
• A non-UK resident individual letting residential properties in the UK.
• An individual letting residential properties in a partnership.
• A trustee or beneficiary of trusts liable for Income Tax on residential property profits.

The finance cost restriction does not apply if you are a:

• UK resident company
• Non-UK resident company

These entities will continue to receive relief for interest and other finance costs in the usual manner.