Long Accounting Period CT600
Periods over 12 months automatically split into two CT600 submissions
Why Use This Feature?
How It Works
Enter your accounting period (up to 18 months)
TinyTax detects periods over 12 months automatically
First 12 months becomes CT600 #1, remainder becomes CT600 #2
Profits are apportioned between the two periods using HMRC rules
Submit both returns to HMRC from one workflow
Who Benefits?
New Companies with Long First Periods
Incorporated mid-year and chose an accounting reference date that creates a 13–18 month first period? TinyTax handles the split automatically.
Changed Year-End
Extended your accounting period to align with a parent company or new financial year? File both CT600 submissions in one go.
Accountants Filing Complex Periods
No more spreadsheet apportionment. The split, the maths, and both filings are handled by the software.
Frequently Asked Questions
How long can my accounting period be?
HMRC permits accounting periods up to 18 months. TinyTax supports periods from 1 day up to 18 months. Periods over 12 months automatically split into two CT600 submissions.
How are profits apportioned across the two periods?
Profits are split based on the number of days in each period (HMRC's standard apportionment method). TinyTax calculates this automatically — you don't need to do the maths manually.
Do I file the accounts twice?
No. Companies House accounts cover the full long period (a single set of accounts). HMRC requires two CT600 submissions because corporation tax periods can't exceed 12 months — each CT600 covers part of the accounts.
What about marginal relief and tax rate changes across the periods?
Both CT600 submissions get correct tax rate handling. If the period straddles the 31 March rate change date, profits are further apportioned and the right rate is applied to each portion. Marginal relief thresholds are also adjusted for short periods.
Ready to Get Started?
Join hundreds of UK micro-entities using TinyTax to file CT600 and accounts
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