What is the HMRC upload size limit?

HMRC limits document attachments to 2MB per file for self-assessment and other submissions. Scan P60s and payslips at 150–200 DPI then compress to stay under 2MB.

Is there a limit on the number of PDFs I can merge?

No hard limit is enforced. However, since the files are processed entirely securely's RAM, combining very large files (e.g. over 100MB total) may depend on your device memory.

Can I adjust the page order inside a PDF?

Our tool merges documents in the order you list them. If you need to separate and re-order pages, you can use our Split PDF tool first, then merge the parts.

Is my personal data secure while merging PDFs?

Yes, the entire merge process happens in your local browser sandbox. No document data is sent to our servers, keeping your private certificates completely secure.

Merge PDF for HMRC

Combine multiple PDF documents or certificates into a single file. Control order, sort pages, and optimize output size.

Official Requirements for HMRC

To ensure your document is accepted by the United Kingdom government authorities, it must meet the following strict criteria:

Maximum File Size: 2048 KB
Self-assessment attachments: max 2MB per file.
Accepted formats: PDF, JPEG, PNG.
Tax return supporting evidence must be clearly legible.
P60, P45, and payslip scans must show all text clearly.

Disclaimer: These requirements are verified based on official guidelines. However, immigration and examination rules can change. Always consult the official HMRC portal before final submission.

Common Rejection Reasons

File size over 2MB.
Corrupted or password-protected PDF.
Document not legible after compression.

How to Use Merge PDF for HMRC

Follow these simple steps to ensure your file meets all requirements for HMRC.

Choose PDF Files

Select two or more PDF files from your device to merge together.

Arrange File Order

Drag and drop the files in the list to arrange them in the exact order they should appear in the merged document.

Merge and Download

Set your target size constraint and click the merge button to download the combined PDF.

Frequently Asked Questions about HMRC

Answers to common questions regarding requirements for HMRC.

What is the HMRC upload size limit? HMRC limits document attachments to 2MB per file for self-assessment and other submissions. Scan P60s and payslips at 150–200 DPI then compress to stay under 2MB.: HMRC limits document attachments to 2MB per file for self-assessment and other submissions. Scan P60s and payslips at 150–200 DPI then compress to stay under 2MB.
Is there a limit on the number of PDFs I can merge? No hard limit is enforced. However, since the files are processed entirely securely's RAM, combining very large files (e.g. over 100MB total) may depend on your device memory.: No hard limit is enforced. However, since the files are processed entirely securely's RAM, combining very large files (e.g. over 100MB total) may depend on your device memory.
Can I adjust the page order inside a PDF? Our tool merges documents in the order you list them. If you need to separate and re-order pages, you can use our Split PDF tool first, then merge the parts.: Our tool merges documents in the order you list them. If you need to separate and re-order pages, you can use our Split PDF tool first, then merge the parts.
Is my personal data secure while merging PDFs? Yes, the entire merge process happens in your local browser sandbox. No document data is sent to our servers, keeping your private certificates completely secure.: Yes, the entire merge process happens in your local browser sandbox. No document data is sent to our servers, keeping your private certificates completely secure.

Free related tools to prepare your documents.

Split PDF

Split PDF documents by custom page ranges or extract specific pages securely with zero data leakage.

Compress PDF

Compress PDF files to a target size secure. Optimize scanned documents and certificates with zero quality loss.

JPG to PDF

Convert JPG, JPEG, and PNG images into PDF files. Automatically scale and compress pages to fit under your desired limit.

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