Quarterly Tax Check-Ins: A Simple Routine to Avoid a Surprise Bill
Quick Answer
Check your numbers once a quarter (every 3 months). Review income, expenses, profit, and estimated tax. Adjust what you're setting aside. This 15-minute habit prevents the January panic and ensures you're never surprised by your tax bill.
Disclaimer
This tool provides estimates and organisation help only. It's not financial advice. Always check HMRC guidance or a qualified accountant for your situation.
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The January Shock (and How to Avoid It)
Every January, thousands of self-employed people get an unpleasant surprise: a tax bill bigger than expected.
The problem isn't complicated. It's that they waited until year-end to look at their numbers. By then, it's too late to adjust.
Quarterly check-ins fix this.
When you review your finances every three months, you:
- Catch problems early (income dropping, expenses rising)
- Know exactly how much to set aside
- Enter January confident, not panicked
- Build a habit that pays off year after year
The Numbers That Matter
Your quarterly check-in focuses on four key figures:
1. Total Income (Year to Date)
How much has come in since April 6th? This is your gross turnover—everything before expenses.
Why it matters: Your income drives your tax calculation. If it's higher than expected, your bill will be too.
2. Total Expenses (Year to Date)
How much have you spent on allowable business costs? This reduces your taxable profit.
Why it matters: Claiming all legitimate expenses lowers your tax. But you need to track them to claim them.
3. Profit (Income Minus Expenses)
This is the number you pay tax on. Not your income—your profit.
Why it matters: Higher profit = higher tax. If profit is growing faster than expected, adjust your savings rate.
4. Estimated Tax and NI
What will you owe on January 31st? A good calculator shows this based on your current figures.
Why it matters: This is the number that determines whether you're saving enough.
The 15-Minute Quarterly Routine
Here's exactly what to do at the end of each quarter.
When to Check In
The UK tax year runs April to April. Quarterly check-ins naturally fall around:
| Quarter | Period | Check-In Window |
|---|---|---|
| Q1 | April – June | Early July |
| Q2 | July – September | Early October |
| Q3 | October – December | Early January |
| Q4 | January – March | Early April |
Pick a specific day (e.g., first Monday of the month) and add it to your calendar.
Step 1: Update Your Figures (5 Minutes)
If you're tracking monthly:
- Make sure all income for the quarter is logged
- Import or enter any missing expenses
- Check categorisation is correct
If you're using CSV import, this might just mean uploading your latest bank export.
Step 2: Review the Dashboard (3 Minutes)
Look at:
- Year-to-date income: On track, ahead, or behind?
- Year-to-date expenses: Higher or lower than usual?
- Current profit: Where are you compared to last year?
- Estimated tax: Has it changed significantly?
Note any surprises. A quiet quarter might mean lower tax. A busy quarter might mean you need to save more.
Step 3: Adjust Your Savings (5 Minutes)
Based on your estimated tax, check you're setting aside enough.
Quick formula:
Amount to set aside = (Estimated annual tax ÷ 12) × months remaining
If your estimate says £8,000 and you're at the end of Q2 (6 months left), you need £4,000 saved. If you've only got £3,000 saved, increase your monthly transfer.
Step 4: Lock the Quarter (2 Minutes)
If you're preparing for MTD (or just want clean records):
- Mark the quarter as "final"
- Export a summary for your records
- Move on—don't revisit unless something's wrong
What to Do When Numbers Surprise You
Scenario: Income Lower Than Expected
Possible causes: Slow period, lost client, seasonal dip
Actions:
- Check if this is temporary or a trend
- If persistent, consider adjusting your monthly savings target down
- Look at whether expenses have stayed the same (they might need trimming)
Scenario: Income Higher Than Expected
Possible causes: Big project, good quarter, seasonal peak
Actions:
- Good news for your business, but watch the tax impact
- Increase the percentage you're setting aside
- Consider if expenses should be higher too (investing in growth?)
Scenario: Expenses Higher Than Expected
Possible causes: One-off purchase, subscription creep, genuine growth costs
Actions:
- Review each category—any surprises?
- Check nothing personal has crept in
- If legitimate business expenses, enjoy the tax reduction
Scenario: Tax Estimate Jumped Significantly
Possible causes: Higher profit, threshold crossed (NI, higher rate tax)
Actions:
- Don't panic—you have time to prepare
- Increase monthly savings immediately
- Check for missed expenses that could reduce the bill
Tools That Make Check-Ins Easy
A Good Dashboard
You need somewhere that shows your key numbers at a glance. Logging into multiple places and adding up spreadsheets defeats the point.
Look for:
- Year-to-date totals for income and expenses
- Live estimated tax calculation
- Monthly breakdown to spot trends
Expense Import
Manual entry is tedious. Bank CSV import gets your transactions in quickly, so you can focus on review rather than data entry.
History and Comparison
Seeing this year vs. last year gives context. Is income up 10%? Are expenses in line? This comparison makes patterns obvious.
Quarterly Lock
The ability to "lock" a quarter means you know those figures are final. No accidentally editing old data. Clean records for MTD or your accountant.
How Dude, What's My Tax? Helps
We've built features specifically for the quarterly check-in workflow.
Live Tax Estimate
As you add income and expenses, your estimated tax updates instantly. No manual calculation needed.
MTD Quarterly Mode
Lock each quarter's figures once you're happy. See Q1, Q2, Q3, Q4 totals clearly separated. Export quarter summaries as PDF.
Expenses CSV Import
Import your bank transactions instead of typing them. Auto-categorise, set business use percentages, and see monthly totals immediately.
History & Analytics
Compare this year to previous years. Spot trends in income, expenses, and profit. See how your tax position is developing.
Planner (What-If Scenarios)
Test scenarios: "What if income grows 20%?" or "What if I claim £2,000 more expenses?" See the tax impact before it happens.
Building the Habit
The first few quarters might feel awkward. Here's how to make it stick:
1. Calendar It
Add recurring calendar events for your check-in dates. Treat it like a meeting with yourself.
2. Keep It Short
15 minutes is the goal. If it's taking longer, you might need better tools or simpler processes.
3. Celebrate the Clarity
Each check-in should leave you feeling informed, not stressed. If you're consistently surprised, the routine is working—you're catching things early.
4. Share If It Helps
Some people find accountability useful. Tell a partner or business friend when you've done your quarterly check-in.
5. Review the Routine Annually
At year-end, ask: Did this routine help? What could be simpler? Adjust for next year.
Quarterly Check-Ins and MTD
From April 2026, many self-employed people will need to submit quarterly updates to HMRC under Making Tax Digital (MTD).
The quarterly check-in routine prepares you perfectly:
- You're already reviewing figures quarterly
- Locking quarters becomes second nature
- The numbers are ready to submit (via compatible software)
- No scrambling when MTD becomes mandatory
Even if you're not required to use MTD yet, the habit is valuable.
FAQ
How long does a quarterly check-in take?
Around 15 minutes if your systems are set up. First time might take longer as you get organised.
What if I miss a quarter?
Just do a catch-up. Review two quarters together. It's not ideal, but better late than never.
Should I check more often?
Monthly is fine if you prefer it. Some people like weekly income tracking. But quarterly is the minimum for avoiding surprises.
What if my income is irregular?
Even more reason to check quarterly. Irregular income makes estimation harder—regular reviews keep you grounded in reality.
Do I need accounting software?
Not necessarily. A simple tool that tracks income, expenses, and estimates tax is enough. Full accounting software is optional.
What about Payments on Account?
If you owe more than £1,000 and less than 80% came from PAYE, you'll make payments on account. Quarterly check-ins help you anticipate this and prepare.
Can my accountant do this for me?
Some people have accountants who provide quarterly reports. That works too. The key is that someone is checking regularly.
What if my estimate is very different from last year?
Investigate why. Big changes usually have clear causes: major client won/lost, big expense, life change. Understand it, then plan accordingly.
Next Steps
Start your quarterly routine now. You don't need to wait for the end of a quarter—just check where you are today.
See your current figures, estimated tax, and set up your first quarterly check-in.
Learn more about MTD preparation or explore expense tracking with CSV import.
Back to the Learn hub.
This guide is for general information only. Tax rules change, and everyone's situation is different. Always check the latest HMRC guidance and consider speaking to a qualified accountant if you're unsure.