Martin Lewis Says Do THIS Before April — The Deadline That Could Cost You £1,000

Introduction: Why April 5th Matters

Every year, Martin Lewis and the MoneySavingExpert team highlight one of the most important financial deadlines in the UK: April 5th . This single date marks the end of the UK tax year, and missing it could cost you hundreds—sometimes thousands—of pounds in lost allowances and tax relief.

But here's the thing: most people don't realise just how many opportunities exist before April 5th. The deadline isn't just about filing your tax return. It's about maximising your ISA allowance, making pension contributions, claiming marriage allowance relief, reclaiming Gift Aid, and strategically using your capital gains allowance.

we'll walk you through every single action you should take before April 5th, ranked by the financial impact each one could have on your wealth. We'll cover the most valuable opportunities first, so you can prioritise your efforts.

1. ISA Deadline - Your Most Flexible Allowance

The Individual Savings Account (ISA) is one of the most powerful wealth-building tools available to UK residents. Every tax year, you can contribute up to £20,000 to any combination of ISA types, and all interest, dividends, and capital gains grow completely tax-free.

Why ISAs Matter Before April 5th

Unlike pension contributions (which you can carry forward with some restrictions), unused ISA allowance is lost forever. If you don't contribute your full £20,000 by April 5th, that allowance disappears. Over a lifetime, this compounds dramatically.

Types of ISAs to Consider

• Cash ISAs: Best if you want guaranteed returns and no risk. Current rates offer 4-5% on fixed deposits.
• Stocks & Shares ISAs: Best for long-term growth if you can tolerate market volatility. Ideal for most working-age people.
• Lifetime ISAs: Only for first-time homebuyers or those saving for retirement. Includes government bonus (£1 for every £4 contributed, up to £1,000/year).
• Innovative Finance ISAs: Higher risk, higher potential returns through peer-to-peer lending.

Action Steps for Your ISA

1. Calculate how much you can afford to contribute between now and April 5th
2. Decide on your ISA type based on risk appetite and time horizon
3. Open an account if you don't already have one (can be done online in minutes)
4. Set up the transfer of funds immediately—don't wait until the last moment
5. If using Lifetime ISA for a house purchase, ensure you're eligible (first-time buyer, under 40)

Pro tip: Some people spread their £20,000 across multiple ISA types. For example, you could put £5,000 in a Lifetime ISA (plus £1,250 government bonus), £5,000 in a Cash ISA for emergency funds, and £10,000 in a Stocks & Shares ISA for long-term growth.

2. Pension Contributions Before Tax Year End

Making a pension contribution before April 5th offers immediate tax relief—potentially 20% to 45% back on your contribution, depending on your tax band. This is one of the most tax-efficient ways to save.

How Tax Relief Works

• Basic rate (20%): You put in £80, the government adds £20 (gross £100)
• Higher rate (40%): You get an additional 20% relief through tax return
• Additional rate (45%): You get an additional 25% relief through tax return

Annual Allowance and Carry Forward

Most people have an annual allowance of £60,000 that can be contributed tax-efficiently. Unlike ISAs, you can carry forward unused allowance from up to 3 previous tax years—but only if you were a member of a pension scheme in those years.

Who Gets Most Benefit?

Higher and additional rate taxpayers benefit most. A £10,000 pension contribution costs them only £6,000 (if additional rate) but could be worth much more long-term. Basic rate taxpayers still benefit, but the government tops up less.

Action Steps for Pensions

1. Check your current pension statements for existing balance and last contribution
2. Contact your pension provider to confirm available carry forward room
3. Calculate how much you can afford to contribute
4. If you need to claim higher rate relief, ensure you'll complete a self-assessment tax return
5. Make the contribution before April 5th (confirm processing time with provider)

3. Marriage Allowance - Free Money Waiting

Marriage Allowance is potentially hundreds of pounds free each year if you're married or in a civil partnership with a large income gap. Incredibly, millions of eligible couples don't claim it .

How Marriage Allowance Works

If one partner earns less than the personal allowance (£12,570 for 2025/26) and the other earns more, the lower earner can transfer their unused allowance to their partner. This can save up to £252 per year .

Eligibility Checklist

• Married or in a civil partnership
• Both living in the UK
• At least one of you born after 5 April 1935
• Neither entitled to certain benefits
• One partner earning below the personal allowance
• Other partner earning less than £12,570 plus the lower earner's unused allowance

Important: Retrospective Claims

You can claim Marriage Allowance up to 4 years in arrears. If you've been eligible but never claimed, you could receive back payments totalling over £1,000. This must be done before April 5th for the current tax year.

How to Claim

1. Visit gov.uk/apply-marriage-allowance
2. Sign in with Government Gateway credentials (or create an account)
3. Provide partner details
4. Confirm eligibility
5. Submit claim

The process takes 15 minutes and applies immediately from the date submitted.

4. Gift Aid Reclaim - Boost Your Charity Giving

If you donate to registered charities and pay UK income tax, Gift Aid effectively increases your donation value by 25% at no cost to you. Beyond that, higher and additional rate taxpayers can claim even more relief through their tax return.

How Gift Aid Works

• You donate £80 to a charity
• The charity claims Gift Aid and receives £100 (£80 from you + £20 from government)
• If you're a higher rate taxpayer, you can claim additional relief (difference between 40% and 20% = £20)
• Your total gift of £80 becomes worth £100+ to the charity

Four-Year Claims

Just like Marriage Allowance, you can claim Gift Aid relief up to 4 years in arrears. If you made donations in previous years but didn't claim Gift Aid relief on your tax return, you can go back and claim now.

Claiming Higher Rate Relief

You must complete a Self-Assessment tax return to claim the additional relief. Keep records of all charity donations and claim before the April deadline.

5. Capital Gains Tax Allowance Strategy

Every tax year, you have a Capital Gains Tax (CGT) allowance—£3,000 for 2025/26. Any gains above this level are taxed at 10-20% depending on your income level. Strategic selling before April 5th can optimise this allowance.

The CGT Planning Window

If you have investment assets (shares, second properties, cryptocurrency) with unrealised gains, selling before April 5th and repurchasing afterwards crystallises those gains within the current tax year's allowance, potentially saving tax.

Example Scenario

You own shares worth £15,000 that you bought for £12,000 (£3,000 gain). Here's what you can do:

1. Sell shares before April 5th for £15,000 (realise the £3,000 gain)
2. The £3,000 gain fits within your £3,000 allowance (£0 tax)
3. Immediately repurchase the shares for £15,000
4. You now have a higher cost base (£15,000 vs £12,000) and have realised gains at no tax cost
5. Any future gains are calculated from £15,000, so your next gain won't occur as quickly

Married Couple Strategy

Married couples have two separate CGT allowances (£3,000 each = £6,000 total). If one spouse has significant gains, transfer some assets to the other spouse before selling to utilise both allowances.

6. All Time-Sensitive Actions Ranked by Impact

Here's the complete ranking of April deadline actions, from highest to lowest financial impact for the average UK household:

Why This Ranking Matters

The ISA and pension deadlines offer the largest potential benefits and should be your priority. Marriage Allowance, while offering less money, requires almost no effort, making it a quick win. CGT planning is valuable but requires more financial knowledge and planning.

Complete Action Checklist

Use this checklist to ensure you don't miss any April 5th opportunities:

Frequently Asked Questions

Can I contribute to an ISA after April 5th?

No. Your ISA allowance for that tax year is lost. The new £20,000 allowance starts on April 6th for the new tax year. This is why the deadline is so critical—you cannot carry it forward.

What's the difference between the tax year and calendar year?

The UK tax year runs from April 6th to April 5th (not January 1st to December 31st). This is why April 5th is the important deadline—it marks the end of that tax year.

Do I need to be employed to claim pension tax relief?

No. You can contribute to a personal pension (SIPP or self-invested personal pension) and claim relief up to your gross income. Self-employed people and even those not working can contribute.

Is my charity donation eligible for Gift Aid?

Only if it's to a registered charity. Check the Charity Commission website (www.charitycommission.gov.uk) or ask the charity directly. Political parties don't qualify.

What happens if I miss the April 5th deadline?

For ISAs, your allowance is gone forever. For pension relief, you might be able to claim through your tax return, but timing becomes trickier. For Marriage Allowance, you'll miss the year but can apply next year. Best practice: don't miss it.

Can I contribute to multiple ISAs in one year?

Yes, you can split your £20,000 allowance across multiple ISA types: one Lifetime ISA, one Stocks & Shares ISA, one Cash ISA, and one Innovative Finance ISA. You can only have one of each type per tax year.